<human>: Can you provide a brief overview of the text?

So I met her through a friend about a year ago. Haven't seen her since then, until this weekend when she approached me at the bar. We talked for the better part of an hour, got her number right before she left. Texted her later that night, and she told me to come over to a party she was at. We ended up fooling around (everything but having sex) and fell asleep together.

I found out the next day after I dropped her off at home that she is in a relationship. When I confronted her about it, she said that she's been seeing red flags pop up recently, and things have been getting pretty rocky. She said how talking to me at the bar turned her night around completely, and how great of a guy I am. She talked with her SO last night, and decided to try and work things out with him. Not gonna lie, I'm a bit disappointed because I had developed an interest in her just beyond having someone to hook up with. I'm not sure if she told him that her and I hooked up. I then told her I probably won't be talking to her anymore, and she responded by saying something along the lines of being disappointed that I feel that way, yada yada. Apparently she still wants to be friends.

Am I being put on the back burner, maybe as a fall back in case she decides to dump her current BF? Also, who's to say she wouldn't cheat on me in the same fashion if her and I start dating?
<bot>: Hooked up with girl in a relationship which I found out about after the fact.  Developed small feelings/interest before finding this out.  What should I do?