As a guy who has seen women do the same thing to men, I think that humanity sucks rather than just men or just women.
Inevitably, the dumpee is going to fret about what they did wrong and therefore convinced the dumper to break-up with them. Having been on both sides of this equation it's made me deal with relationships with more respect and civility. It's never easy to tell someone they're not your idea of a "mate", but if we realize the pain and confront it, perhaps we'll be better off. And don't forget karma: you can't forget about THAT.
I'm sorry you feel so sad. I had a bad break-up with a shithole, she-devil about 1 1/2 ago and it still grieves me to think about all the love and dedication I gave her. The good news is, I rarely consider her anymore. It might take a while to get him outta your head, but that WILL make life easier in the future...I know that doesn't make you feel better right this second, but it will make you stronger and more perceptive in the years to come.
Keep it real.