My best friend cheated on her boyfriend... with me

Last night I stayed the night with my friend. We smoked weed and talked for a while. It was around three in the morning. She asked me how I knew I was bisexual (she’s been questioning her sexuality lately) and so I told her my story. We were in her bed and she kept getting closer to me until we were nose to nose. And then she kissed me. And kept kissing me. I was really confused but I went along with it. I just followed her lead and did the things she wanted to do. Things kept escalating, there was touching, but never went under the panties. We eventually went to sleep around four in the morning and I woke up to her texting her Boyfriend like everything was normal. I just feel confused and a little guilty and I don’t really know what to do at this point. She’s confused too since it was her first time doing anything with a girl. What should I do?