Hrmmmmmmmm Sorry Marky but I gotta disagree with you :s
If this guy is such a jerk he can humiliate ditch his girlfriend in front of her friends then the last thing she should be doing is trying to make it work.
Sally? I know it's hard but you have to make yourself realise that this guy is not worth your effort or tears, take a few days to be miserable, eat chocolate, get all your girly friends round and moan about guys and slag him off as much as you possibly can until it's out of your system, then once you've done that, move on with your life safe in the knowledge that someone better is waiting for you *hugs*