Fight back [i]only[/i] when necessary, but do not give yourself over to the hatred. Learn to forgive, as well. Self defense is important. Protecting others is important. 

Vengeance, pay back, putting another person in his place, letting your emotions get out of control, or justifying your violence with "logic"...These are not important and--even worse--self destructive and only continue the violence.

Fight back to protect what you love--not to destroy something you hate.

Edit: I'm a pacifist and an optimist--sometimes an idealist--so feel free to disregard this: violence will never solve the heart of the problem.