How to overcome HATE?

Hate is one emotion which I actually hate. I have not allowed this to creep into my system even after someone butchered me completely in past. But this time I find it extremely difficult to overcome this emotion.

But I ask myself that why should someone hate another human. Isn’t it true that after we start hating someone, we actually rent out a room in our brain for that person. We brood and cuss but that person who did something bad with us ends up living peacefully leaving us to suffer.

But still, why do we find ourselves hating others?

According to me, we can only hate someone whom we loved truly at some point and when they hurt us plus when even after hurting they do not realize what a great deal of discomfort they have caused in our lives. My two cents on this: if the person does not realize what a jerk s/he is then s/he does not deserve any thing from you including your hate AND if the person does realize that maybe should consider forgiving them.

What do you think? Should we hate?