The tension was palpable between Addison and Mark as they stared at each other. Their eyes met, but neither of them seemed to know what to say.

The silence grew heavier and the nerves were impossible to hide on their faces. As time went on, Derek became increasingly confused as he saw that neither of them spoke.

What was it that Addison wasn't going to tell him? And why did Mark know? Why did they both seem like they had just come out of a cemetery on Halloween night?

Finally, and after seeing that Addison wouldn't take the initiative, Mark took a deep breath and broke the silence.

"I... I overheard you talking about Addison's abortion, I didn't wanna interrupt... it's just that we discussed this earlier and I didn't think she'd tell you about it..."

"What abortion?" Derek turned frightened to look at her. She was pale and almost unresponsive. It was as if she had truly frozen inside.

"Listen, Derek, it had nothing to do with you, she and I..."

"Addison, you had an abortion?" Derek continued asking, ignoring Mark. He wasn't interested in hearing anything Mark had to say. "When? No... it's not possible, I've been with you this whole time, yesterday... yesterday we saw the baby, I... " his throat started to close from anguish.

"Yesterday? What do you mean? What did you see yesterday?"

"Derek..." Addison whispered as she saw him starting to panic.

"Addison, tell me this is all a sick joke, the calculations don't add up, less than 36 hours ago we were hearing the heartbeat, when did you get rid of the baby? How could you do this without discussing it with me first?"

"What heartbeat? Addison, are you pregnant again?" Mark asked, even more confused. It seemed like a madmen conversation.

"What do you mean by again?" Derek turned to look at Mark. Then they both turned to look at Addison, she was starting to cry.

"Addison?" Mark angrily demanded.

"I'm pregnant," she finally said with a choked voice, "and our baby is fine," she looked at Derek.

"I can't believe you're pregnant again. Not after what you did last time... you... you're the worst, Addison," he looked at her with hatred and left the office.

"You aborted Mark's baby," Derek said with the same expression that Mark had just had moments ago.

"Derek... it happened before I came to Seattle... I..."

"I can't believe you did that. I can't believe you got pregnant by him... when I look at you, I feel nauseous."

"Derek..."

"You said it was only once. You cried and swore to me that it was only once!"

"And it was... when I told you, it had only been once..." tears streamed down her cheeks one after another.

"So there were more times after that."

"Yes..."

"And you got pregnant."

"Yes..."

"Is this baby mine or did you sleep with him the last time he was in Seattle?"

"Derek, no..." that last question pained her. She could physically feel that pain. Her crying intensified.

"Do I need a paternity test?"

"I haven't slept with Mark for over a year!" she sobbed with a trembling voice.

Derek wasn't entirely convinced still. After this, he doubted everything Addison had ever told him. What had been true and what hadn't? How many more things happened during those 3 months they were apart from each other?

"How many times were there?"

"I don't know..."

"HOW MANY?"

"I DON'T KNOW, DEREK! WHAT DO YOU WANT ME TO SAY? SIX? TEN? THIRTEEN?"

"YOU QUICKLY WENT FROM A ONE-NIGHT STAND TO A DAILY SEX ROUTINE WITH YOUR LOVER!"

Derek was out of control, aggressively shouting. Addison was frightened, unable to stop crying desperately, and begging him to calm down. But that was impossible. They had ignited the fuse of a bomb that had just exploded in their faces.

After a while, they both calmed down. If Richard heard the screams coming from Addison's office, they would be fired without notice.

"You're such a whore."

"Can you let me explain things without insulting me? Please."

"What else are you going to explain? What string of lies are you going to make up now?"

"I fell in love with him, or at least I thought so. I wanted to convince myself that I hadn't thrown away eleven years of marriage for a one-night stand. I wanted to convince myself that I had a new chance to start something with someone who would love me, who would desire me. You left me, Derek. You didn't answer my calls, or my messages. You quit your job, you moved away. The first few weeks, I stood by the front door of our house every day, waiting for you to come in and tell me that everything would be okay, that we could move forward as we always had. But that never happened! Weeks went by and you never came back. I had to accept that it was all over. And Mark... Mark was there, he was always there."

"And that's when you decided to start a family with him? Because he was always there?"

"Of course not, Derek. It was an accident."

"It's incredible how, being a gynecologist, you have so many accidents."

"You have no right to blame me for this. You left me. You left. You were sleeping with an intern fifteen years younger than you while married to me. You were cheating on me too! You never told her you were married! You cheated on me the same night you invited me to that damn prom!" she cried again. "I was just a few meters away from you when you slept with her in an on-call room, without caring if it was your workplace or if your stupid wife found out. You have no right to blame me, Derek! You're just as dirty as I am."

He was silent. He knew that Addison was telling the truth, but his anger and disappointment didn't allow him to acknowledge it. He wanted to run away and never see her again. He really wanted to be able to go to another city -or another country if possible.

"If Mark was such a big part of your life, why didn't you have that child? Why did you come back to me if you had already accepted that we were over?"

"Because Mark wasn't what I expected. I don't know if he was in love with me or not, but he wasn't ready to be a father."

"And for that stupidity, you had an abortion? I don't know if I'm ready to be a father either, after all."

"Do not speak of my abortion as if it were a simple thing, a cold, just another anecdote. I will not allow it. It was a decision that still hurts me to this day. I don't regret doing it, but that doesn't diminish the suffering I went through. I became attached to that baby. Mark was excited, he had bought a Yankees onesie and marked the due date on his fridge calendar. We were sure it was going to be a girl, and we were going to name her Ella. And we grew to love her during those days. But things don't work out as one wants. In week 4, almost reaching week 5, Mark slept with one of the nurses in the maternity ward. One of those who worked with me daily. And a few days later, I found him with another one in the medical supply room. How could he not even respect me knowing that I was pregnant with his child?

"Does that surprise you? What can you expect from a guy like Mark Sloan?"

"At that moment, all the flashes of my childhood came rushing back. Lying to Bizzy, telling her that I had gone out for ice cream with Dad when in reality I had been sitting in his office drawing all afternoon while he slept with his secretary next door, or with the cleaning lady, or with any of my French, tennis, or piano teachers. Or with a colleague from work. Or any woman with a pair of legs. Mark... he was the younger version of my father. And I didn't want to bring a child into the world to experience the hell I had to go through.

"I... I'm sorry for that, Addison..."

"All the times I had dreamed of having a baby, it had been with you. Not with him. I didn't want to be tied to him for life, much less have a child to suffer with. I made an appointment the next day at an abortion clinic without telling him. It was quick, four misoprostol pills every 3 hours, painkillers for the pain, and pads to control the bleeding. It was one of the worst days of my existence. Mark found out when it was all over and he was furious at me. That same night, I received a call from Richard asking me to fly to Seattle for a case, and I accepted. Because my life, my illusion of life, with Mark, ended the exact moment I saw him in that closet.

"I'm sorry you had to go through that..."

"Yeah, and I'm even sorrier. But you had given me another chance. You had accepted me moving in with you in the trailer. You were going to try again. You gave me hope and made me believe that it had all been worth it.

"And wasn't it?"

"I don't know, Derek. My life wasn't happier in Seattle. You didn't make it easy for me. I had to accept your daily mistreatment because I deserved it. Your reproaches. Your shouts, insults, and nicknames. The judgmental stares of everyone at the hospital because I was the bitch who cheated on the perfect McDreamy. The hatred from Meredith's intern friends. I had to accept living in the middle of the forest without clean water, electricity, almost no signal, in a 12-meter dwelling, exposed to any type of wild animal, cold, heat, giving up any kind of luxury... and all for you to end up doing the same thing Mark did to me.

"I... I'm sorry. I shouldn't have called you a whore.

"No, you shouldn't have," she said, wiping away the tears that had inevitably been flowing from her eyes as she explained what she had gone through.

"I'm sorry. I... I know I haven't done my best to save the relationship. It was very hard for me to leave the city where I lived the best years of my life, you know? I couldn't stay in that place knowing that the love of my life had betrayed me with my life partner. How could I go out and not see you in every corner of the city that was supposedly ours? Every space screamed your name. Our streets, our hospital, our walks in Central Park, our favorite shops and restaurants, our friends, our family. Everything was ours, and I needed to escape to a place where I wouldn't feel any kind of emotion," he sighed and paused for a long time.

Addison looked at him with tear-filled eyes. Perhaps this was the first time both of them were truly opening up to each other.

"I got in my car and drove aimlessly all night until I didn't recognize the path I was on anymore," he continued. "I didn't intend to arrive in Seattle, in fact, I realized I was there once I arrived. I spent a few days in that city reflecting, and I remembered that Richard was the chief of one of the hospitals in the area. I didn't need to interview for the job, and that same day, I started working here. In my fresh start. I met Meredith that night too..."

"Oh..."

"I didn't plan on falling in love with her. I didn't think I could ever have eyes for another woman besides you. But... it happened. I needed her to forget you. To not think about the hurt you and Mark had caused me. She gave me the breathing space I needed because I felt like I was suffocating. Addison, I loved you like crazy, more than anyone else in my life. The day I told you I wanted to spend eternity by your side, I wasn't lying. And Mark... I've known Mark since I was four years old. I didn't even know how to write my name yet, and Mark was already there by my side. He has been there through all the stages of my life. He was my twin brother from another mother. Do you understand the level of betrayal I felt? The two people I trusted and loved the most in this life stabbed me in the heart. I needed to leave, I needed to run away. I'm sorry if you felt rejected, and if I act with indifference. It's something I still can't control because I still can't forget it. You were right when you said I hadn't forgiven you, because it's true. And I truly hope that someday I can, because there's nothing in the world I want more than to love you again like I did when I was a first-year medical student who didn't even know how to hold a scalpel. I want to be that person again, and I want you to be the person you were."

"I want us to be who we were too..." she said in a voice barely above a whisper. She was still stunned by everything she had heard.

"Please, don't abort this baby. I need this joy in my life, it's been my lifelong dream."

"I'm not going to do it, Derek, please. Who do you think I am?"

"I can't promise that our relationship will be perfect in the future, because it's something neither of us knows, but what I can promise is that I will be a good father."

"I know..."

"And this baby will never, never feel unwanted. I will always be there for him or her, no matter what. Do you hear me? I won't leave you or the baby alone for a single moment."

"I need you, Derek. I'm scared all the time..."

"I know. And I'll always be here for you," he sat down next to her and she hugged him.

They stayed like that for a while, silently embracing, contemplating everything they had said. It had been one of the most intense but necessary discussions they had ever had.

"Poor baby, I wish it had been born to normal parents," Addison said, placing a hand on her belly.

"It's a Shepherd, it will never be normal."

"Excuse me? Montgomery Shepherd, you mean."

Derek couldn't help but laugh. She always had a perfect comeback for every sentence he said, and he remembered that was one of the things that made him fall in love with her.

Now, they just had to remember everything else.