I'm not saying your situation is at all fair but ... the word "hate" makes you a slave. You're obviously thinking about this situation as you're reading this thread and I hope you're not obsessing on it at other times. The down-side to a situation like this is that your psychopath manager isn't spending any time thinking about you (outside using you to create value for himself). If you're obsessing over him, he's won. As someone else said, get yourself out of there. And once you have, forgive and forget (for your own piece of mind).

Note that I don't mean that you should forget enough to end up in this situation again ... or go back to work for him for some reason. Just enough to let you go on with your life without obsessing over the past.