just find out the truth and move on.
or have sex with your girl one last time and take a dump on her face. she'll never get over that, and then go beat up the guy. that should help you feel better and you would always have a great story to tell.
seriously, whatever does come out, i'm sorry if its true. its a crappy feeling being betrayed.good luck.
Good luck honey!!! I hope it's not true. Please just relax and like the others said, get all the facts. Your friend was hysterical and devastated as well. Sometimes people just say things so that others can feel what they are feeling. Please keep us posted.