Well, if you put it in the "Gender and Relatioship" category, I am assuming you mean a romantic partner who hurt you. At this stage I have two advice.
1. Always remeber, when you lost the girl you love and you are sadden by it, ask yourself this question, would you feel hurt if you never know her, in other word, pretend you never met her, you can't lost what you never have or you never know.
2. This one apply for guys only. Go get laid, find a girl and have sex with her, if you can't get laid via ethical method, go buy yourself a prostitute for one night or go to a strip club, if you dare, the girl that hurt you would mean so much lesser to you afterwards