My gf cheated on me help?!!?

ok one, that was to long man, but simple, SHE CHEATED ON YOU! once a cheater always a cheater, and if she cant make her mind up on which one she wants that even spells trouble for the future. Because if you did take her back, and those feelings for the other guy came back up, she will do it again. so KICK HER TO THE CURB AND GET ONE THAT WONT STAB YOU IN THE BACK!!