Odin: I definitely know how you feel. Perhaps not to the same extent, but I remember that feeling of being lost, disconnected, like nothing will ever be bright again. It took me about six months to get over it when it happened to me. I think my "mourning period" so to speak was breif compared to alot of people's. I still have residual left over from my experience - I think I wasn't good enough, pretty enough, etc...Then logic sets in. The guy was horrible for me. But those negative feelings STILL resurface.
When you have that much emotion invested into one person, it hurts when they leave you (or in my case, thrust you away because he's a fucking self-absorbed alcoholic asshole who's still hung up over a manipulative, dishonest, using piece of...GRRR! *twtich*) Sorry...but bottom line is, it hurts. Alot. But eventually things start to heal. It takes awhile, but eventually you'll get back to a reasonably happy state of mind.
But right now, you don't HAVE to be. Right now you get to be sad and depressed. Your friends will be there for you, though. And friends are always good at helping a body through this kind of sadness.