Om Swami
Why do I hate someone, and is my hatred really justified?
Hatred is usually conditioning
Hating or disliking someone is usually a product of conditioning. Ask who decided that what they did was wrong, and whether you were ever entitled to what you feel they took.
But who said that what they did was wrong? You feel that because maybe they deprived you of something. But who's to say that you were going to be blessed with that to begin with?