Sorry to disappoint, but I'm not going to yell at you or tell you what a freak you are. There's nothing wrong with you. What you have are fantasies that society deems "abnormal" or "unacceptable." However, you don't act out on these fantasies. Welcome to being just like hundreds of millions of other people, you twat.
You're in a very unique position with your "sick thoughts" though. Unlike most people who have forbidden desires, you probably can act on yours one day. There's a whole beautiful world of Sado-Masochism out there, just waiting for your to discover it. This isn't like zoophilia, pedophilia, necrophilia, etc. where all you can ever do is dream about the object of your passion and never act on it. No, being a sadist to get your rocks off is totally possible and can (and does) happen all the time among consenting people.
I would suggest looking for some S&M websites and forums to join. They could tell you if what you're feeling is really "normal" for a sadist. They could also help you hook up with others like yourself in your area. You will be helped better by getting support from "your own kind" than by anything I could ever tell you. Go forth, my child, and consult The Great All-Knowing Oracle of the Internets, for it surely has the answers you seek!
Hating you softly,