I am the Co-signer of a student loan - need to know my rights?

I co-signed a student from my brother in 1999. He is currently attending law school and has stopped making payments (he can't get the loan deferred either). The creditor is coming after me and my credit. Recently, my american express was closed due to the "delinquency status of the loan." What can I do? How far can the creditor go? Can I work out a lower monthly payment with the creditor? I don't want to pay the entire amount since I know my brother will never pay me back. We're not speaking any more due to this. How do I get my name released from the loan...I reliaze this may be a little late.?