Who is initially responsible for repayment of student loans if the Signer and Co-Signer are now divorced?

Ex-husband obtained 4 year degree while we were married. He quit his job to go to school full time, forcing us to live off of my measly paycheck and some student loans. I co-signed with him on these loans. Our divorce decree states that he is to get my name off the loans and arrange to make payments for them without jeopardizing my credit. We have been divorced for 4 years and he has yet to follow the divorce decree. In return, my credit is horrible and I constantly have student loan debt collectors calling me because he will not respond to any of their phone calls or correspondence. I have taken him back to court AT LEAST once a year since our divorce for contempt and our judge just tells him to do what the divorce decree says. As you can see, I am getting nowhere with this.