She was scared.
She never expected to be scared when Santana finally admitted her feelings for her, but she was. That was supposed to be Santana's role in the relationship. She did love Santana and she knew that she always would but she doesn't want to be with Santana now if Santana would change her mind at any moment.
Having Santana and then losing her would surely hurt more than this annoying aching pain in her chest at the moment. She kept trying to brush it away. She did love Artie, but it was more like you love a friend or a brother, she never got the same spark when she touched his hand as she did when she and Santana held pinkies and her heart never raced at just the sight of him walking towards her. The first time her heart raced at the sight of Santana she swore she was having a heart attack it was beating so fast, but she is sure that what happens when everyone sees their best friend.
She knew Santana would be hurting but she knew Santana and Santana would simply find someone else to replace her with, because someone as amazing as Santana would never love someone as stupid as Brittany for too long, at least that's what Brittany told herself every time she began to entertain the notion that they could actually be together, Santana was just too good for her.
A part of her wishes that she had never pushed Santana to talk about their feelings, Santana wouldn't be hurting right now and they would still be able to pretend that it was nothing, that they simply made out when they had nothing better to do, because having Santana as a best friend was surely better than having her as nothing.
She has called Santana over 15 times, each time leaving a message; at least she thought she was she always got confused when it came to when to start talking and when to hang up. She is beginning to worry and starts to get ready to go to her house, just to make sure she is alright. It gives her an excuse to cancel her date with Artie because even though she chose to be with him the thought of seeing him right now brings tears to her eyes because he is the reason she doesn't have Santana correction she is the reason she doesn't have Santana. It is then she realises she has nobody else to blame.
She drives the 10 minutes to Santana's house with tears running down her face, and for the first time in years she knocks instead of just barging in, she feels unwelcome and uncomfortable, this is not something she is used to at the Lopez household. After 5 minutes of standing on the doorstep bawling her eyes out she lets herself in, she uses the key that Santana said was only to be used if she was dying or horny, but this was an emergency.
Santana's bedroom made her feel safe, even if they weren't on speaking terms. It smelt like Santana to the extent that she wanted to get on the bed and inhale every inch of it so that the smell would never leave her memory.
She had always known she was stupid but this was by far the stupidest thing she had ever done, after years of pining after Santana she let her walk away? She was going to fix this and she was going to fix it as soon as Santana got home.
Brittany kept drifting off, the smell and the familiarity of the room was just too enticing and even though she was fighting to keep her eyes open she just couldn't, Santana would surely wake her up when she got home.
Hours later when Brittany finally opened her eyes, it took her a moment to realise where she was as her eyes were met with a familiar person that certainly wasn't there before, their chest rising and falling in the deepest, but most peaceful of sleeps. Her arm was wrapped around Santana's waste as if it was second nature. She could wake her up but she looked so beat down and happy all at the same time. She needed sleep and they could talk in the morning, in fact they could talk for the rest of their lives.
She was still scared but it didn't matter, because she had Santana.