Hatred is the refusal to grow up into the realization that the injustice may be irreversible and that it's our business to deal with it realistically. At a fundamental level, hatred is a failure to let go of a wound to one's very sense of self. Hatred is self-splitting. To hate is to make someone else responsible for dressing your wounds. That's one reason why raging victims so often are found in the vicinity of victimizers.
Hatred is an addiction to the perpetrator.
To hate is to look for absolution for having been a victim, whether or not one could help it. When you get right down to it, hatred is back-door, overcompensated impotence. Some debts can't be repaid, only inherited. Forgiveness understands that those who inflict harm must be confronted with the effects of that harm. Forgiveness never submits to an injustice and fights it to the death if need be, but not with the means or weapons of the unjust.