What happens if my ex files bankruptcy

I will assume that you and your ex both signed the promissory note (financing) for the car, and that both of you are on the title.  If this is true, you will receive a notice from the bankruptcy court when he files.  If the car is surrendered to the bank or repossessed (because payments were not made), your credit will take a hit.  Also, if there is a deficiency (there is still a balance due on the note after the car is sold at auction and the proceeds are applied toward the balance due), you could face a lawsuit from the bank for the difference.  If you did not sign the promissory note, your credit will not be affected.