If your ex ran up a bill during the marriage, most states consider it joint debt, even if your name isn't on the bills.

And, yes it's your problem to see it gets paid.

You are also responsible to make sure your name is not on credit lines with your ex-spouse after the divorce.

BUT

If she disclosed the debt and agreed in the divorce to assume responsibility, the divorce documents are your recourse to get the money from her.

If she did not disclose the debt in the divorce, she is guilty of fraud and you can still get the money back from her.  (blood from a stone?)

In both cases, It means reopening the divorce case.   uhg!

My first husband's entire family believed in running up a ton of debt, living large, and let life insurance pay for it later.

He left me with many debts, all in my name (not so stupid, but a real jerk)