If she is already telling other people that she plans on doing it she has already put a lot of thought into it and has found that it is best for her...I highly doubt anything you do or say is going to persuade her to feel any different...IMHO its best to accept it and move on...Maybe to make you feel a little better about it call her on Thursday and tell her you want to break up with her so that way it doesn't hurt as bad...Make plans with your friends to go out to the club this weekend and hook up with some random chick and try to get on the path of feeling good about yourself and knowing that it was her choice and don't let it piss you off because everything happens for a reason.....