Girlfriend says she’s bi and wants to hook up with another woman when drunk. Denies being bi when sober?

I went out with my girlfriend of 7 months with some friends and she got blackout drunk and randomly starts telling me about how she's into women (I had a hunch). I don't really care about that, I've dated plenty of bisexual women before. The problem is that she said she wants to hook up with another woman.

When I asked her about it the next day, she said that she was in a relationship with another girl for a year, but it was years ago and she's not sexually attracted to women anymore, she would never cheat
and she doesn't know why she said that. So now I'm wondering two things.

One: If I should believe she's not actually bi, even some of my friends have noticed different things and brought it up to me. And if not then two: if I should just leave now because she's EXTREMELY touchy/flirty with other women. Before I thought she was just being funny/silly, but if she’s actually bi, it puts all of that in a new light and I’m not gonna wait around to get cheated on.
Girlfriend says she’s bi and wants to hook up with another woman when drunk. Denies being bi when sober?
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