I hooked up with my neighbor who has a boyfriend, and now things are awkward

I (22M) moved into a new apartment about three months ago. I don’t know many people in the city, so I’ve been trying to socialize and find things to do. One of my neighbors is a 27F who lives with her six-year-old son. We exchanged contact information when we first met but never really talked much. Last weekend, she texted me asking for a favor because she’d lost her ID and wanted me to buy her some wine. I agreed, and she invited me over to drink with her. I wasn’t doing anything, so I went. We spent the night drinking, talking, singing karaoke, and dancing. She told me she had a long-distance boyfriend and that he knew I was over drinking with her. As we got drunker, things got physical, and we ended up making out on her couch. Eventually, she felt sick and threw up, so I helped her to bed and went back to my apartment. A couple of hours later, she texted me asking me to come back because she was feeling better. I knew I probably shouldn’t have gone back, but I did. We started making out again, and she told me she wanted to have sex. I hesitated because she had a boyfriend, but I eventually gave in. We had sex, and afterward, I made sure she was okay before leaving. I’d also brought her some ibuprofen because she had a headache. Now I’m sitting here wondering what the hell I’ve gotten myself into. She’s my next-door neighbor, she has a boyfriend, and we’re inevitably going to see each other again. I also feel a little guilty about how drunk we both were that night. I haven’t been back over since, but I know we need to have a conversation about what happened. I just don’t know how to approach it without making things even more awkward.