Vehicle Trade-In

An ex-girlfriend and I took out a car together. After breaking up, she decided to trade in the car and get a new one. The dealership sent me a Power of Attorney form to fill out to have our car used as a down payment for her new one. There was still a balance of $21,000 on it during trade-in. She got the new car with someone co-signing with her. My question is, how long will the car loan be visible on my credit report as an owed amount? how long before that loan amount is removed from my credit report?