Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

Slow destruction on co-signed property
First off learn from this:  Never cosign again.  There are plenty of other "tales of woe" outlined on this site that started and ended similarly. Secondly do what you can to get off of the loan.  First I'd go back to her dad and offer him $1000 to take you off the loan and sign over the car.  Maybe go up to $3000 if you have that much cash.  If that doesn't work go to the bank and offer them half of the loan balance to take you off.  You can sign a personal loan for that amount (maybe).  Whatever it takes to get off the loan.  If she has a new BF offer him the same deal as the dad. Why do you have to do this?  Because you owned an asset that was once valued at 13K and is valued at (probably) less than 4K.  Given that you have a loan on it the leverage works against you causing you to lose more money.  The goal now is to cut your losses and learn from your mistakes.     I feel like the goal of your post was to make your ex-gf look bad.  It's more important to do some self examination.  If she was such a bad person why did you date her?  Why did you enter a business transaction with her?  I'd recommend seeking counseling on why you make such poor choices and to help you avoid them in the future. Along these lines I'd also examine your goals in life.  If your desire is to be a wealthy person, then why would you borrow money to buy a car?  Seek to imitate rich people to become rich.  Picking the right friends and mates is an important part of this.   If you do not have a desire to be a wealthy person what does it matter?  Losing 13K over seven months is a small step in the "right" direction.