My question involves personal finance in the State of: Arizona

I cosigned a car for my ex, and we just split, he refuses to sell the car back, and I can not sell it back without his signature. He is demanding the car back and claims that he will make the payments, and pay me the money that he owes me. If I don't return the car, he will not pay me a cent so my credit will be ruined. I am a college student with limited funds, and I don't want him to ruin my credit, because I want to buy a new house in the next five years after I graduate. How can I get out of this situation without ruining my credit?