Okay so confusing title I know but hear me out: Also this is my first post and I’m on mobile so apologies in advance

So me (18m) and my girlfriend (18f) recently ended our 2 year relationship when we both went to college. I wanted to try long distance and she didn’t want to since neither of us have a car so visiting would’ve been really hard. We still text a lot and are good friends and are still in love, and I want to get back together. Fast forward to my first weekend at school me and some of my new guy friends start drinking around 1 in the afternoon (always a smart start to a day) and eventually some of their female friends come join us that night. One or them (18f) in particular is very drunk and keeps touching my legs and lying down on me which I’m originally very uncomfortable with and keep moving around the small dorm room to avoid her. Eventually I gave up and we sat on the couch together and were cuddling and flirting a bit. She asks me multiple times to kiss her and I tell her I can’t multiple times. A little later in the night we’re hanging out in a different dorm room and she says she wants me to meet these people in the other room which is connected by the bathroom. I follow in not expecting anything to happen and once I’m in the bathroom she turns off the lights and kisses me. I was caught by surprise and froze and then we stop after a couple seconds and I leave. I’ve barely talked to her since. A few days later I was talking to my ex and asking her what she was thinking about getting back together in November when we’ll see each other again and it seems to be going well until she asks if I’ve kissed anyone and I try my best to tell the story I just told. She is understandably very upset and I’ve been trying to convince her since that I didn’t want it to happen.

Do y’all have any advice on what to do? Do I just go ahead and try to move on from my ex? Keep trying to get back together with her? If so how could we possibly move past this?