Before you say something, hear me out.

Now this girl I started hanging out with seemed pretty interesting. We had similar hobbies and connected well

But she was in a relationship with a person for almost a year now. She told me a lot of private things about herself including that she's cheated before. 

Now recently, whenever we hangout, she tried to get physically close to me. Her bf isn't home so we just chill. She rests her chin on my thighs and stuff life that. 

Now she was supposed to get married to the guy. But lately they've been having a hard time and been fighting. I really didn't want to end up in the middle of them but one day while hanging out we drank a lot. One thing led to the other and now I feel like shit 

I didn't want to do this and it was just bad judgement. She insisted on me getting more fucked up. I feel like I destroyed a relationship and I'm not even interested in her romantically. AITA?