Ex- boyfriend and a shared car title

[Teacher6]

About a year ago I helped my boyfriend buy a car. I was the main signer and he was a co-signer because of his bad credit. We havent been together since January and he has the car. Per our agreement, he is making payments to me every month (so I know they arent late) and he's supposed to keep the insurance and registration current. I recently discovered that he has no insurance on the car and the registration is past due. I would like to take the car back and sell it because I'm worried it will get impounded and I will have to foot the bill. What are my legal rights and options? I'm considering trying to get the police involved to get the car back because he wont return my phone calls now that he knows Im aware of the insurance situation.