dont break up with her, it sounds like you really love your girl. true love is hard to find. me and my ex girl had a perfect relationship and i started fucking with hardcore drugs, she stuck by my side but then i fucked up again and she left. its been 2 months since she left and that shit still hurts like a bitch i still talk to her, im trying to get her back but she said she needs more time. im going fucking crazy without her being here by my side everyday. so i guess what im saying is dont fuck up a great thing, she will get over it you guys will go on, and your relationship will grow stronger from it. like homeboy said, you guys werent even going out so you really did nothing wrong, but i do understand why she is upset im sure you guys were all lovie dovie, and you still fucked that bitch, so im pretty sure she thought you were all hers that night anyways. if you really love her and she makes you happy stay with her, and you will get through this.