Is it normal that i have had sex with my step brother?

Okay, so one night I got really drunk with my step brother. I went in my room to go pass out because i was tired. My step brother jumped on my bed and I didn't really care. So I walked in my room and then I fell, after that its all a blur. But i remember laying with him then kissing. I don't remember having sex with him. But in the morning something was up because I was a virgin, and we all know what happens the first time. So he told me what happened. I didn't know if this was normal or not.... So is it? I realize it was a huge mistake and i would never do it again.

But also my bestfriend found out and decided to be a bitch and tell her boyfriend, and her other bestfriend now I don't know what to do about that....