In a situationship with a friend who has a boyfriend.

I (21M) am currently in a situationship with a friend (20F). So basically what happened was- we're both in a same friend group but didn't use to talk much before due to some previous awkward and funny history. Almost 2 weeks ago I did a live band show in my college after which I got drunk and so did this girl. So anytime she would find me around the campus on that day she would hug me. When it was time to return, I asked her not to leave without me because she was so fucking drunk. We left together with a few other friends. Apparently we were really physically close throughout the time in the metro which made the other people uncomfortable.

Now, the next they had an intervention where the girl was informed about this and then she informed me. We started talking. I didn't remember a lot so she was trying to make me remember. While we were having this conversation she writes how I made her feel comfortable and warm that day and that she really likes to spend time with me (before this we had only spent time when we had tea twice). Now at that point I didn't have any feelings for this girl. But gradually as we kept talking and she opened up about how she feels neglected in her relationship of three years. I started caring more about her. We would also flirt a lot, like A LOT.

All this made me start to like her a lot. Now we started hanging out daily after college. But non of the people in the friend group know about us. One day we met at a spot which is ideally where the couples go hangout and I gave a her a bouquet of sunflowers because she said that she likes them. We did the typical couple shit and while returning home in the metro I held her waist and she said, "It made me feel things I shouldn't." Well the other day we're at this shop having tea and we did so much pda that the owner of the shop politely asked us to leave. Internally it felt weird.

I started feeling a lot of guilt in me for doing this to a guy. I mean there were a lot of chances were I could've kissed the girl but I couldn't bring myself up to do it. A lot of times the girl herself leaned in but I still didn't. All this is fucked up because when I ask her to breakup she says she won't and that she'll try to save her relationship and get back with her boyfriend. Thus I have no chance of getting together with her. She doesn't even consider this cheating. The last day when were kinda sexting, only then did she accept that sexting is borderline cheating. Which is really weird. She also doesn't want me to leave from her life. I don't understand honestly!

I might have missed some trivial details but this is what it is. Please suggest what I should do.