So don't ever go back out with her again. Best thing you can do is to ; 1) date someone else, 2) just forget about her (easy to say, hard to do), 3) get your stuff back, and divest (destroy) yourself of anything that reminds you of her, or is from her., 4) find some music that's really hitting your heart, be it unf*ckingly believably angry, or sad, 5) get your emotions out (I was in a band, and wrote lots of angry, angry, angry songs - made for good music). Same thing happened to me about 10 years ago - got dumped by my 4 year girlfriend when I was about to propose to her. Got depressed for two months, listened to Hank WIlliams and the CroMags, rebounded and "dated" anything that had two X chromosomes for the next year, and spent all the engagement ring money on that. Found the love of my life 3 years later, and was glad that the first girl dumped me, otherwise I wouldn't have met her. Men shouldn't get married before they're 30 anyway, as our "stock" becomes more valuable each year. So the short of it is, go bang someone else. That works for most people.