Husbands and wives that pay child support!I need your opinon.?

My ex divorced me 6 yrs ago and failed to put anything in the divorce decree for child support.I'm disabled and my ex gets over $700.00/month from the federal government for my daughter who lives with her. I was paying additional monies to the ex and my financial situation changed drastically the last 3 months.I told my ex I was going to stop sending my monies because the government was sending so much for my daughters support. She will get this money till she is 18 and also till she finishes college.She is 16 now. Can my ex take me to court for more of the same monies I have been sending for the last 6 years? I figure my ex as received over $60,000.00 for my duaghter over the last 6 yrs.