I was reading this book and it says no matter what just act like nothing is wrong, like it does not bother you. Just say hi to her and pay her no attention the rest of the night. Easier said then done, i know but you have to play the game and check your feelings at the door. This will actually make her wonder what is up with you. If she tries to talk to you more, just be like hey i got to go, dont give her more then 10 mins at a given time. Because if you do you look conqured. If she wants to talk about the break up, just say " your right it is the best thing for both of us" By agreeing with her she wont fight with you and your not trying to change her mind. If you dont chase, you dont look conqured, no matter how u may be feeling. Just have fun and look happy,, dont mope around. Look your best and smell good. Talk to some other women too. Dont let her affect you. When you go home u can deal with your feelings. This book says that the same way to get over your ex is the same way to get them back. So have fun, remember there was life before your ex