Ex wants child support reopened, help please!?

I have been divorced for 4 years. My ex and I were married for less than one year and have a 4 year old daughter together. I have been paying child support and am completely current with my payments. I have since remarried and have another child. My wife has also been a very difficult person to be around, and is very manipulative and dishonest. Around 4 months ago we took my daughter to the doctor and found out that my ex-wife's health insurance through her job was no longer active. We asked her to provide proof that my daughter was in fact covered as she is legally required to and its included in my child support. She refused. I also began to see her around town wearing jeans and t shirts during her normal work schedule, and she finally admitted she had quit her job but had started a new business and was making 6 times what I make. She has said this several times since then that she is making tons of money. My daughter stayed in daycare full-time even though I have offered to let my current wife watch her during the week because she stays at home with our son while in graduate school. My ex refused. Last week I was served papers stating she wanted the child support redone because she has no income whatsoever. My ex is a college grad and perfectly healthy, can I claim she is voluntarily unemployed? Or if she is in fact making money how can I prove it (which I don't believe she is, her parents have always supported her even though she is 33)? She has gone on 4 vacations in the past 3 months with her boyfriend where I watched our daughter extra time. I cannot afford to pay any more child support that I already am. I understand that its a rough economy, but then why is she still spending $800 a month for our daughter to be in daycare full-time. Is there anything I can do?