The loan providers say I'm responsible and it doesn't matter what my divorce papers say. Is this true I will need to civil sue the loan holder I co-signed for?
The lender is correct. as far as they are concerned you are equally responsible. They are not a party to the divorce. If your spouse agreed to be responsible and isn't, then you can file an Order To Show Cause in the Divorce Action. Speak to a Divorce lawyer.
The loan provider is not bound by your agreement as they are not a party to the divorce. If they sue you, you can in turn sue your ex for the money.
You are still liable directly to the loan provider, bc the loan provider was not a party to your settlement agreement with your spouse. If your spouse is not paying the loan, you should make a motion in your divorce case to hold your spouse in contempt for not paying as agreed and ask the court to enforce your settlement agreement.