WI child support laws, procedure for collecting back child support

Child support Arrears: My daughter turned 18 in July. She has since moved in with her father in Ill to attend college. He owes me roughly 40,000.00 is back child support-he is now contesting it and has told me he is filing child support chanrges against me becouse she will be a full time student in college. Unless I sign away the back child support he says I will have to pay child support to him the next 4 years? Can he do that? - Is this your question? Add additional information