Addison gasped as she looked at the result of her pregnancy test. A few weeks ago she had made a huge mistake when she had cheated on her husband Derek with his best friend Mark. It was eating her up inside but Derek hadn't come home that night till long after Mark had left. She had washed their sheets and hid any evidence that Mark had been there at all. Now it looked like there would be something that she would no longer be able to hide from him, unless by some miracle she was further along in her pregnancy than she'd realised. It had been a while since she had been with her husband. He had been increasingly absent in the past year and he rarely decided to make any time to spend with her. She had been so upset on that night she slept with Mark, but afterwards she'd hated herself for what she'd done. She didn't want to lose her husband but she felt so guilty. But what was wrong in their marriage wasn't all her fault. But she knew now that Derek wouldn't see that, all he'd do was blame her for what had happened once he finds out what she'd done with his best friend.

She knew that she had to tell him what she had done. But first she wanted to find out how many weeks pregnant she was as if there was a small chance that it was Derek's baby, then maybe there was more of a chance that he'd stay. She knew that if the baby is Mark's then she'd lose him for good.

She made an appointment with her gynaecologist and the next day she found out the news that she was 5 weeks pregnant. The baby was definitely Mark's. Addison felt a tear run down her cheek. She made her way home and tried to build up the courage to tell Derek.

Derek arrived home a few hours later and Addison looked up from where she was sitting.

"Hey how was work?" She asked him.

"Fine. Busy. I'm really tired Addison." Derek answered.

"Well I need to tell you something and you're not going to like it but I have to get this out."

"What Addison?"

"I.. I slept with Mark."

"You... You what? Is this some sort of joke?"

Addison felt a tear run down her cheek. "No.. I didn't mean to. I made a huge mistake and I'm so sorry Derek. I was upset and you're never here and Mark.. He was just here. I'm so sorry."

"I can't believe this! When did this happen?"

"5 weeks ago. I'm so sorry, Derek. It happened once and I understand if you never want to see me again. I wouldn't blame you. I love you and I'm just so sorry. There's more.. I just found out that I'm 5 weeks pregnant."

"You screwed my best friend and he got you pregnant? Is that what you're saying Addison." Derek shouted.

"Yes." Addison whispered as tears ran down her cheeks.

"I can't believe this. You're my wife Addison and he was my best friend and you've both betrayed me. I can't bare to look at you a second longer."

"Look I'll go and give you some space."

"Going to go and tell Mark the good news about his baby?"

"No Derek. I.. I wish this baby was yours and that we were still the happy couple from all those years ago. But we've been falling apart for a long time and I may have broken us completely. But you played a part in it too."

"Yeah well I'm sorry I was busy saving lives but how would you feel if I'd slept with your best friend and got her pregnant?"

"Look I get it. I'd want to kill you and her. I can't make any excuses for my actions and I get that what I've done is unforgivable. But I love you Derek and if there's any chance for us after you've had time to process this or if you want this to end and we get a divorce then I understand."

"What about the baby? I mean are you having the baby?"

"I.. I just found out yesterday but I think so. I've always wanted a baby and it wouldn't feel right to abort this baby and then try and have another one. Even though this wasn't an ideal situation to have a baby. I don't think I can Derek."

"Fuck Addison. I just can't believe that you and him would betray me like this." Derek shouted and punched a hole in the wall. Addison flinched but she knew Derek would never hurt her physically. He may smash up the house and she'd give him that, but she knew he'd never hit her.

"I'm so sorry, Derek. I'll uh pack some things and go to a hotel."

"No.. No you stay here. I don't think I want to be in this house. Is this where it happened? Did you.. Did he fuck you in our bed?"

"Yes." Addison admitted.

Derek shook his head and gave her a look of disgust.

"Well then.. I'm not staying here but first I'm going to give that so called best friend of mine a piece of my mind."

"Please Derek don't! I... I can't deal with him knowing this right now. I don't want to be with him. It was a huge mistake. I know he has the right to know eventually. But please Derek." She pleaded.

"Ok. But I'm going to go. This is beyond betrayal Addison. Right now I don't know if I ever want to see you again."

"Ok." Addison whispered as tears streamed down her face.

Derek looked at her once more then stormed out the house.

xxxxxxx

Months had passed and Addison hadn't heard from Derek since. She guessed just like he'd told her that he never wanted to see her again.

Mark had been trying to convince her to give him a chance and that he'd be good to her and the baby. But she didn't want that. She didn't love Mark. She loves Derek and even if he never takes her back she doesn't want to be with Mark. Of course she'd let him see the baby, but that was the only contact she wanted with him.

Her baby was growing bigger by the day and she'd found out she was having a girl. Even though she'd lost her husband, she couldn't regret her baby girl. She guessed she'd just have to accept the fact that she was now going to be a single mother.

She looked up as the phone rang and she answered it.

"Hi Addison. It's Richard Webber."

"Oh Hi Richard. How are you? How is Adele and things in Seattle?"

"Adele is on holiday in the Virgin Islands and look I don't know how much you know but Derek is here in Seattle."

"Oh. I... Thank you Richard. I don't know what he's told you but, I did something terrible and he left me and I understand that he wanted to get away from me, but it's nice to know where he is and that he's safe."

"I just thought I'd let you know he was here before I asked if you wanted to come here to Seattle for a TTTS case?"

"Oh, of course I'll come Richard after all I'm one of the few people in the country who can perform that surgery. I don't want to upset Derek but it would also be nice if we could sort something out, and not be stuck in this limbo. If he wants to divorce, then I understand. I'd rather we get it over with if that's what he wants. I love him, Richard. But I understand if he can never forgive me. I slept with his best friend, in our bed and it was a huge mistake but then I found out I was pregnant and the baby isn't Derek's and I had to tell him."

"Oh Addie. I'm so sorry. There's something else you should know.. I saw them a few days ago. Derek and an intern here, they were kissing."

"Oh.. Thank you for telling me Richard. I'd rather know now than find out when I got there. At least now I'm prepared for what is going to happen to our marriage."

"Also I don't want you to worry about me, as I'm getting better now but I had a tumour and Derek operated. I haven't called Adele yet as I didn't want to spoil her holiday but I wanted you to know before you came."

"Oh I'm sorry Richard, but Derek is the best so you were in safe hands and I'm glad you're getting better."

"Thanks Addie. So I guess I'll see you sometime tomorrow?"

"Yes I'll look at flights now. Thank you Richard."

xxxxxxxxx

Derek rejected yet another call from his wife. Why was she ringing so much today? Since he'd been here she had called a lot at first but then it had died down when she'd got the message that he wasn't going to answer, and now she was calling again. This was a bad sign, maybe he should answer and see what she had to say for herself. But she couldn't know he was here in Seattle could she, unless Richard - no he guessed she'd just got sick of Mark cheating on her and wanted him back. Well he was with Meredith now and his wife and her adulterous love child were not going to be ruining the life he was building for himself here in Seattle.

Meredith had come to meet him in the lobby and they were just about to leave when he saw a flash of red hair. He had to admit that she looked stunning. Meredith paled in comparison to Addison. When he saw her it was like no one else existed for him, but he quickly shook that thought out of his head. She had cheated on him with his best friend and he had every right to move on.

Addison tried to give her most confident look as she walked in and saw her husband helping his new girlfriend put her coat on. It hurt so badly to see, but she knew she couldn't blame him as she had done much worse. She tried to keep her composure as she walked up to them. Derek was going to hate her even more for this, but she couldn't seem to stop the words that came from her mouth. Telling Meredith that Derek was her husband. She was ready to fight for their marriage, and she wasn't about to let go without a fight.

"Hi I'm Addison Shepherd."

"Shepherd?" The girl asks.

"And you must be the woman who's been screwing my husband."