My ex husband put my name on his car loan as the co signer without me knowing.
What can I do?
First, ask the company who claims you are a cosigner to forward a copy of the document showing your handwritten signature (A: to verify you didn't actually sign it, and B: so you have evidence of ID theft). If they can't, write them a letter, return receipt requested, you are not liable until they provide proof (and maintain a copy for your records plus any responses they provide).
If you did sign, you are liable for the loan and responsible for the debt. In this case, get in writing from the loan company the "settlement in full" amount (if it does not say that the amount is settlement in full, don't pay it). Write a check and make sure the account is CLOSED! Make sure the letter clearly states to close the account and remove your name as a cosigner. As always, return receipt requested and keep a copy of the settlement in full letter to you, the letter you send, image of the check that went with it, and any response they provide.
If it's not your signature, do you have ID theft protection? If so, report it to them and they can guide you through the process. If not your signature and you do not have ID theft protection, report it to police to get a report that this was ID theft. This will require reporting your ex to police (Do not lie about or intentionally leave out anything, or you'll be guilty of falsifying a statement to police). Write a letter to the loan company stating you are a victim of ID theft, you are not legally responsible for the debt and any attempts to collect will be treated as harassment for which you will pursue legal action. Return receipt requested. Provide a copy of the report. Keep a copy of everything you send and receive.
Unfortunately most debt collectors don't have brains and will continue to harass you unless you pay it. Keep a record of all written correspondence and calls (dates, times, what was said). If it gets excessive or goes on for months, retain a group like collection bully.
Some resources about how to deal with collectors: https://www.daveramsey.com/blog/get-rid-of-debt-collectors https://www.daveramsey.com/blog/the-truth-about-debt-collectors https://www.daveramsey.com/blog/debt-collectors-get-money
The most important thing is to deal with it immediately. This will keep coming back to haunt you if you ignore it. As the articles indicate, NEVER give electronic access to your accounts and don't let them get you worked up.
You call whoever issued the car loan, and tell them that you did NOT sign this document. And that if there is a signature that looks like yours it is a forgery. That is if you want to get your husband into trouble. Which would be very understandable.
I noticed you wrote "x husband" which I assume means ex-husband. So tell the issuer of the loan, and tell the police.
Possibly, if the car was purchased during the marriage.
If it was after the marriage, he cannot make you liable. When exactly the marriage ended varies by state.
If it happened during the marriage, the divorce court should have made a decision about who got the car and who got the payments. For obvious reasons, they usually make this the same person! So it is unlikely they would award him the car and you the payments.
You should tell this company quite definitely that you are divorced and you are not liable for his debts. Yelling at them on the phone does absolutely nothing. you need to do it in writing. From your post I am guessing that writing is not your profession, so you might use your county's legal aid society to have someone help write that letter for you.