Ex husband stopping kids insurance

Ok so went through a nasty divorce. Ex husband is in the airforce and couldn't handle married life. So when our son was 4 months old he asked for a divorce. Which was ok because he was extremely abusive. Anyways now In our divorce paper it states he is to have them insured. They have always had tricare prime which is free.. but since our divorce I moved back home and apparently prime is not in contract with the pediatricians here. So after months of arguing with this man about our kids needing to be seen at the dr bc our daughter has medical problems that make her go every month plus son having asthma and always getting bronchitis from daycare and constantly sick. I had enough of him not caring so I called and changed it over myself. At least then my kids could get in and be seen by the dr. I have been paying all the Co pays and medicine which have been alot!! And paying all the dr bills. Well during an argument with the ex I told him I changed it already and he changed it back. Taking our kids pediatrician away. He said I cannot afford a medical bill if you get in a car wreck. So you will change the common cold Turing into the flu and them dying from the flu or bronchitis turning into pneumonia? Over the chance I might get into a wreck (have not had any accidents thank god). I make to much for government assistance but not enough to pay the over 400 cobra insurance my work offers for family... is he this much of a pos that he would really put money ahead of his kids. I'm like so your taking the kids insurance away from them so you don't get a medical bill that you may not even get!! But he just bought a brand new f350 Ford truck... how much did that cost you next to your harley you bought last year... I'm so fed up with trying to make him care for our kids and putting them first. How do I make sure the kids get the insurance they need so they can have a pediatrician. There has to be some rule against this. The closes dr that accepts the insurance he is willing to give them is almost 3 hours away. It has to be within so many miles of a base to have prime. I've contacted his first sergeant. He said he will handle it and if I needed any thing else to call him. Now I'm not about messing with his career but our kids need things it took me almost 2 years to get new updated ID cards from him. All he had to do was sign sign a paper and I could get their new cards for their insurance info. 2 years... He only calls maybe once every two weeks or longer. Our daughter just had to stay at the Dr's bc they thought she had type one diabetes and he called a week later to find out the results. I spent 3 days in a different town waiting on the test and dr and he couldn't even call. What do I do to make sure they get what they need. Sorry it's so long.