What to do when my ex stops paying her part of the debt?

We were married and the divorce declared we split the debt in half. Well in April of last year she contacts me and says she isn't paying her part anymore because she has a new baby and doesn't have the money. Long story short, we agree that she'd send in her engagement ring which was rightfully mine anyway since she broke up with me, to help cover part of the debt. I've been paying on the bill since April because it'll effect my credit. But she paid on the bill for over two years proving she was supposed to pay that. Now, she calls me, says she pulled her credit report and thinks it says I hadn't paid on the bill since June. Well, I never knew she was on the credit card to begin with. She says she is buying a house. She left me with a 8000 bill when I have my own debt from our marriage I'm paying off. In Kansas, small claims court is 4000. I can't afford an attorney at all. What should I do?