Being in a mental hospital does not automatically make you incompetent to sign a legal agreement. If you were thinking clearly enough to seek out an attorney then you could also make a legal agreement. It doesn't matter that you lied about your assets. I think you'll find that you have to pay. If you go to court on it you'll be paying another attorney fee with no guarantee that the first fee will be dropped.

I know when I'm manic I can't just return things I buy because of it. You are always responsible for your actions.