Please HELP me! I need advice on what to do about my liar ex-husband!?

I have been divorced for 5 years now, and have been getting child support on and off for all of these years. We have two children, whom he has only asked to see twice during all this time. They don't even know him anymore, but every time I have talked to him about visitation I have been nice and willing to let him see them. When we went to court for our final divorce hearing, he lied and told the judge I wouldn't let him see the kids...then I had to sit and listen to the judge tell me I can't do that (It was horrible, I wasn't even allowed to speak my point!). Well, now he hasn't paid in a couple of months and owes a total of $5K to me, and I filed for contempt. The prosecutor's office, whom I have been working with a lot, said they recently received a letter from him "a sob story about visitation". I knew this would happen! He will not accept blame for anything, and now that he is supposed to show reason as to why he hasn't made a payment--he is going to try this again! I need help =(