Sorry I didn't see this sooner. I think that you and your father should first consult a lawyer to understand any possible legal ramifications - and then if its possible the two of you should either buy out or fire your brother.

Also, check out the internet or the bookstore for books/articles that deal with the psychology of family businesses.

Google something like "family business stress" and you'll be on your way. You'll either be directed to books to buy or you might be able to find online reprints of articles that deal with exactly what you and your father are going through right now.

Finally, I agree with Cataholic - prepare for the idea that you won't work there anymore by having your resume ready. In fact, there's nothing to stop you from starting the process now. Employers tend to want to hire people away from other people, so the best time to look for a job is when you have a job. This will at least remove some of the anxiety of what will happen in the future.