IMHO Descent is not really enjoyable if you have a hero player with a really big mouth and dictating how the other players should be running their character. Another poster said earlier that somebody is his/her playgroup had to leave because of that very reason. If you're still there and reading, then I would actually give your friend a favor and re-introduce her back into your group and kick out the douchebag. If people cannot behave then nobody is having fun, thus there is no point having game sessions. Doesn't feel like these are times where people with a normal life would enjoy additional stress and arguments with their friends.
I play with a fairly experienced group of players and there is one player that I sometimes have trouble playing with for this very reason. Some people forget that they are playing a game with/against other human beings. When they behave that way, they make the game less enjoyable to other human beings.