Refer to this thread.

I don't recall feeling truly betrayed in a long time. Why? I stopped trusting people a long time ago. Even my close family, even my parents. I don't trust anybody or anything, not even myself. I have no expectations of the future. Thus, I never feel betrayed, let down, or disappointed in any way. Everything bad that happens is just something I can easily shrug off.

This usually helps me not to feel the need for revenge. Sure, I may get a tingling sensation of wanting revenge, but it passes fairily quick.