My xwife was supposed to pay a judgment off with the money she received from our divorce settlement. It's written specifically into the agreement that her now former attorney was going to handle arrangements. She didn't pay and now the company is trying to garnish my check. What can I do to avoid paying this bill twice?

Ask the divorce court to hold her in contempt for failure to abide by the decree.

But that won't stop your creditor from garnishing your pay. The creditor had no control over whether your wife or her attorney did what they were supposed to do.