Legal Question in Credit and Debt Law in Wisconsin

Technically, everyone always has the right to not pay a disputed debt. However, defaulting on a provable contractual obligation also creates a right for the agrieved party to sue you, leading to a costly process which can damage your credit and end up costing you more than you could have originally paid to settle the debt. Your "ex" might also be able to sue you for "unjust enrichment." On the other hand, if you do go to court and the Judge decides that there was no contract for you to repay the money or that it was a gift, you would not have to pay it back at all. I do not know enough about your case to suggest which outcome is more likely, so you need to either consult with an attorney and furnish more complete information or decide to take a chance and "let the chips fall where they may," if he really sues you.