Who does my husband pay?

[caw2323]

My husband has been divorced from his ex-wife for almost 8 years. They have 2 children together. Their divorce decree states that they split the medical expences 50/50. However, until 2 years ago, we always paid 100% because we knew that she wasn't financially able to pay her half (her fault because she couldn't keep a job). My husband is very non-confrontational, and just wants everyone to be happy. Two years ago she remarried, and now has a husband that makes a lot of money. They moved an hour away, and our 50/50 visitation has gone down more and more over the last 2 years. She hasn't told him of any doctor appointments the children have been to since she remarried. Yesterday we received statements showing that her and her husband have spent about $4,000 on medical, dental, and pharmacy bills over the past 2 years, and she wants her half from my husband. Is he obligated to pay her directly for those bills (some dating back 2 years) even though he has paid way more out of pocket over the last 8 years?