being sued for medical expenses dad is responsible for

i live in new york state. i am supposed to be helped by the jefferson county support collection unit. i am being sued for back medical expenses thst my ex husband is supposed to be paying. he makes $45,000/year plus works for cash on the side. i make $18,000/year and have all the bills because i have always carried medical and dental coverage on the children (3). he dropped his family coverage becuse he thought it was to expensive. i thought under new york state law if he had coverage on himself he had to carry the children. th e court said that he was in violation because he dropped the coverege and made him 100% responsible for a period of time. now he is only responsible for 73% after my insurance pays and he still pays nothing. he says he is paying his $30 toward his arrears and that should cover it. i am filing another violation of medical form through the support collection unit and will go before the hearing examiner again. any help i can receive will be greatly appreciated.