I 'stupidly' co-signed a car loan to help a co-worker and good friend. He has paid one month late already, and damaged my credit score. I will pay on-time from now on (assuming he doesn't). In order to protect my credit. If I have to pay to keep the account from being 30 days late, can I sue him for the amount I paid? Also, if he doesn't repay me after a court ruling, can I put a lien on the vehicle and take it?