Ok, first of all, you don't black out and have sex with someone. Seriously. In my younger years, I got ridiculously drunk and high to the point that I couldn't manage a sentence, but when I had sex with someone I damn well knew it. My inhibitions were obviously way down, but I knew what was going on and with whom. He wasn't sleeping with a mindless zombie. So you're buying that crap awfully easily.
Secondly, why are you wasting so much time on worrying about how guilty this is making her feel? She is very clever in turning this around and making it a 'woe is me' situation. "Oh I cheated on you and poor me I'm just SO humiliated and GUILTY. No, no....don't feel sorry for me. It was a drunken mistake I had no control over and shouldn't be judged for, but I'm JUST SUCH an AWFUL person." She's totally taking away from your feelings and your right to be upset. In that sense, she's disrespecting you again.
If you knew when to walk away from a situation I would say you'd have been out the door already. But you clearly want to believe her so badly that you're really making excuses left right and centre. This is a two month old relationship, you've invested nothing in it and she's already shown her true colours. Man up and move on already.
Good christian girl? Sad christian hypocrite is more like it.
Live as if you were to die tomorrow. Learn as if you were to live forever. - Mohandas Gandhi