I am divorced, but my ex still wants to be medicaly covered, however my union says not valid

I have been divorced from my wife since 2011. The judge says that I have to pay alimony and child support. I am also responsible to keep them on my Government Union medical. However, the union bylaws change constantly. All 3 were taken off. I was able to send the birth certificates for my children. However they want something that says, that I have been living with her or have a joint something with my ex. I have neither, as I am living with my fiance and our daughter, and bills and are in both our names. My ex is now trying to get 8 more years of alimony and demanding that the union put her back on my medical. Am I legally responsible. My union says they are not responsible for her since we are no longer married or living together. And that she is to get medical through the NYS Health Marketplace. What do I do? I don't make enough since the child support and alimony already leave me below poverty level.