I've been there. But the thing is, with or without you, life goes on. You can deny that all you want, but whether or not you believe it, this life is too damn short to waste being bitter. If you just sit on some ratty old couch and watch TV all the time or pretend you're a nympho in some nasty little Internet chat room and never come away with anything to show for it, that's not living. That's existing, and being miserable while you're at it.
People only fail when they stop trying to succeed.
Now before you call me a sentimental idiot for saying that, I want you to look at a living failure. Take some pathetic old guy with a beer-gut and sunken eyes who just lies around all the time. Maybe he's even your dad. If he were still trying, he wouldn't say that. He would be alive with the hope of what he still could be.