Speaking as an accountant.
I want back an reread the OP. First question: can you afford the payment? If yes, the value of the house is irrelevant, you have an obligation to pay the money back. Failure to do so is going to ruin your credit for a very long time. It is one thing to get into trouble in a down economy, it is something else to decide you don't feel like doing what you said you were going to do. FYI, your car loses a bunch of value the second you drive it off the lot. This does not relieve of the need to pay the money back.
If the answer to my question is no, Robdar is absolutely right. You need responsible legal counsel to steer through the problem. A bankruptcy court can force a creditor to reschedule a debt. They're called "cram loans" as in "the judge crammed this crummy loan down our throats." Banks hate them, but I suspect the courts don't care much about the banks just now. Or the court may make you sell the house, but it may be able to protect some of your equity.
My .02 on the subject.