I have been VERY irritated lately for reasons I won't go into. However, I have always believed that success is the best revenge. This belief has helped me my whole life. When someone really pisses me off, I don't bother trying to get even with that person. What I do is try even harder to be successful.
My reasoning has always been, why on earth should I put effort into even thinking about someone who doesn't care about me, or has screwed me over. Another belief I have is that everyone gets what they deserve in the end. Not necessarily at the end of each day, but sooner or later. People like that getting what they deserve, in part because eventually only people like themselves will associate with them, but that's another post, part of which I wrote here.
If you believe that your best revenge is by getting extremely successful and showing them - damn them - that you don't need them anyway, then it motivates you to work harder, to do more. In the end, regardless of whether you make up with that person, never see them again or see them on the FBI's most wanted list, the result for you personally is the same - that you are more successful.
And really, it only makes sense that you should put your efforts into yourself and those who care about you and not waste your time and energy on people who don't.