Let's try again. I thought I was being rather clear as to why you should leave instead of kicking the other guy out, as Josh alleges. But people will read into things what they will.
The DM allowed him special privileges (that funny PrC, and allowing him to wipe the party, for instance). That means he is likely to rule in the guy's favour. You have two choices:
- Tell him to stop being an ass and you can both enjoy the game, or
- one of you (probably you, because of the DM thing above) can leave the game because you are no longer enjoying it.
Either way, what do the other people in the group think? If they are also dissatisfied with the current arrangement, it gives you more options.
Remember, life is too short to game with asshats.