Drop her like a hot rock and never look back. exact same thing happened to my best friend, only they had been dating for 2 years. you really really need to move on and fast. i wouldnt even talk to her again until you are completely 100% over her. dont feel sorry for her at all and sure as hell dont feel bad for leaving her. she was the one that got drunk and humped some other dude, now she has to pay the consequences. i know its tough man, believe me, ive also been there, but the best thing for you to do is just realize ur above her and you dont need stuff like that in ur life. i understand that ur gonna do what ur gonna do, and that a few internet posts from people you dont know probably arent gonna change ur mind, but im tellin ya man, youre better off without her.