My wife and I were divorced a few years back. In the divorce decree, we agreed that I would pay child support to her provided that our two sons were attending college full time (12 credits or more). For one and a half years my ex-wife accepted child support payments. Then I found out that our sons were only attending college part time (6 credits). Also, both sons are working, and leasing apartments. I went to court and succeeded in stopping my child support obligation. But now I want the $36,000-plus that my ex-wife fraudulently accepted returned to me. Can I sue her in civil court?