You have, no doubt with good intentions, helped a bad debtor get a loan so the loan is in your name. The fact you gave him the money is of no consequence to the lender. He is of course morally liable to you but don't hold your breath. The lender will pursue you for the money, this is one of those situations where you should perhaps have realised that the whole reason this transaction is necessary at all is because son in law has a bad credit record so could not get a loan himself, hence he has a dishonorable nature hence he will not think twice about not paying mum in law. Very little you can do, I'm afraid, you are relying on a conscience suddenly being created.