I actually got my AH's mail while he was in rehab a couple weeks ago and he had a new credit card in the mail and there was also one with my name on it going to his PO Box. I called the credit card company and asked about the card saying I had not authorized it. He is the one that got the credit card and put me on as an authorized user, therefore I am not responsible for payment, even though we are married.
The beginning of last year, I called our credit card companies and canceled every single one of them. There was one that indicated they needed him to cancel it, not me. I simply said, if that's the case, then I am not responsible for payment, right? they canceled the card.
CANCEL THEM!!!! You can also tell them the situation and close that account and get a new one that he doesn't know the number. Save yourself the worry and frustration, it is just a phone call away - and most have 24 hour customer service!
I don't know your situation, can you ask him to help you make your car payment? If he refuses, can you get together in black and white every transaction HE has made, and show him in black and white how much money he owes you and tell him you really need his help to make your car payment. Sometimes I had to SHOW my AH things in black and white to help him get a reality check of how things really are.
Good luck with this situation.