Well, there's nothing wrong with feeling angry. But the anger does have to go away at some point. I spent a couple years angry and therefore snappish and it did nobody any favours. It also made my insomnia worse and tended to trigger mood swings sometimes.

So, I guess, don't feel guilty about your anger--it sounds like you've got good reason to feel slighted by life--but try to work through it, see what's on the other side.