Did I cheat?

I got black out drunk and I kissed this girl at this all girls party. I was a plus one so I didn’t know anybody but my friend who brought me.

She didn’t see me kiss the girl BUT another girl told my friend she thinks that she saw me and the other girl kiss.

And I truly don’t remember nor do I think I would. I have a bf and I’m not sure what to tell him I feel like it’s something I should come clean about but I’m also not sure if I did.

He has a past with an ex who cheated on him and I don’t want him to feel like he can’t trust me and our relationship dynamic change. Especially if its over something that I’m not sure happened. But I don’t wanna keep secrets from him either Any advice?