Get your own an [broken link removed] (ICB) report to see what loans are in your name and if they are in arrears.
If you have a joint account, contact your bank to ensure both of your signatures are required for withdrawls. Close any such accounts as soon as possible.
Do the same with credit cards you may have jointly.
The point is, find out what is in your name and what you have jointly. It would stop the uncertainty.
If you have items in common, then stop the other person abusing it.
Take control of your own finances. Don't get into revenge...
Other person's behaviour may just be them acting out emotionally. If you can get some mediation going, just to sort out the practical stuff, it may help.
I'm assuming that this is a no going back situation?
Best of luck.