I lied to my girlfriend about our first kiss

I'm 17(M) and about 2-3 weeks ago, i got drunk and kissed my best friend. I wasn't ready to tell my girlfriend again so when she asked what happened at the party, I just told her a lie. <br>I told her another boy kissed me, not a girl and thankfully she believed me. I dont wanna lose my girlfriend, i dont feel bad about the fact that i dont like boys. It was just a random moment at a party while we were both drunk and having fun. Now im gonna break up with my girlfriend tomorrow. <br>Edit: We've been together since last year and she doesn't feel comfortable with me drinking at party and normally i dont, this was my first time. So that's why she got mad. Also, no one knows about my sexuality yet.