Yeah, that is odd. I’m surprised that it hasn’t been charged-off after all these years. I don’t know much about repos, but I think your report should be showing only the balance that was left after they sold your ex’s car. Were you ever notified about the sale?
Here’s something I just found online about disputing repos that might help:
Challenge the factual errors in the listing on your credit report. The loan balance, opening date, high credit, and other errors within the listing can be disputed. As with other factual credit disputes, challenge one listing at a time with the credit reporting agencies.
Always ask for a deletion of the entire listing, not a correction. And never give the credit reporting agency the information needed to correct the error, let them do their job and investigate. Besides, you want the item deleted, not corrected. If the first item you dispute is corrected, move onto the next factual error and again ask for a deletion.