I have a girlfriend who at the begining was very in love with me and would do anything for me. I tried to dump her and sh came back begging. now she is pregnant and keeps on trying to brake up with me. and when I accept it then she call me and tell me that she wants me. Please tell me what to do.

Stick with your guns. If you break up with her because she is playing these attention-seeking games, then she doesn't deserve you to cooperate when she says she wants you back. You're too good to play all of these petty games. If you two aren't broken up at the moment, maybe explain to her that the games need to stop. If she plays dumb, then do the preemptive breakup (saw it on Seinfeld)! If she really wants you, she'll come crawling back. She'll probably do more than just ask as well.

The fact she's pregnant (with your child) makes things a little more complicated though.