Mean people suck. Hang in there. If you sort of get used to the idea that this person isn't going to play fair, it can be fun watching them tie themselves in knots. And you'll always have the upper hand because you won't expect anything from him, won't believe anything he says, and will pretty much be able to predict whatever he tries to pull next. It really can be a lot of fun. Every workplace has bastards, so you might as well learn to find them amusing. It makes life nicer.
So really, this is your big chance to learn how to play with sharks. Which is a very necessary skill if you're ambitious. It's actually an opportunity. I wouldn't trade my five years with the devil for anything.