Most of the time, I try to see the positive in situations and people. There are some good reasons for this - one is that you don't know what's going on in other people's lives when they're mean to you. Another is more selfish - why feel bad if you don't have to?!
It's hard to accept and even harder to enact, but you have the power to decide how you feel. Whatever someone else does to you, you shouldn't let them have that power over you. Recognise that they do NOT have control over your feelings. Rather, YOU do, and as such it is your responsibility to rise above how others would make you feel and take control of your own mind.
It's not easy, especially when you feel that your indignation, fury, frustration and grief are justified. The thing is that, although they may be justified, they're not helpful. They don't make you feel any better long-term. Sure, in the short run, it helps to let it all out, but ultimately you need to get over it.
To help you in that little transition period - the period which comes between, "SO ANGRY!", and, "I still think it's unfair, but I'm not prepared to sacrifice my own happiness for it" - here are some little quotations I've found on the good ol' internet. They cover something of a spectrum - enjoy.