After less than a year, the other half owner recently acquired $200k in cash and wants to leave us. He doesn't want to pay any more into the house. He doesn't realize that by abandoning the house the lender will call in the loan and he'll have to pay his half with nothing to show for it. He thinks he can just walk away and leave us with the payments. We cannot afford to pay the full morgage payment on our own. Nor do we want to lose the house. He is also the type of person that cares less about others, but is only interested in what serves him best. Would it be fair to ask him to pay his half of the house loan, and then offer to let him stay as long as he wants with no further monthly payments, and no other monthly bills? The man is single, in his 70s, and really has no place to go. He is quite paranoid and doesn't trust anyone, not even us anymore. He also has three pets. He thinks he can take his $$ and live anywhere he wants, but an abandonment will show badly for him.
Additional Details
We got an all-interest loan because the sale of his old house would pay it off. After closing, he banked the money.(If you haven't figured it out by now, the man is my husband's father.) The papers we signed on this house said that if an owner abandons the property, the lender can call in the entire loan amount. We do not want to lose the property and we cannot afford the entire monthly mortgage on our own. Neither can we pay off the entire loan amount. This would force a sale. If we lose the house, we have no place to live and our credit would be ruined. We cannot even get a small loan in this situation. Right now we are over $500k in debt with his dad and will never recover if he walks without contributing something toward the house. When he was really sick and needed to be removed from his old house, we were the only ones in his family willing to help him. He offered to give us everything, but all we wanted was to help him get better and keep the house. We