Legal separated - estranged wife secretly transferred debt

After being legally separated for about 8 months, my estranged wife secretly transferred 5400 to one of my credit cards from one of hers. I did not learn of this until after the settlement agreement. Is it illegal for her to have transferred money to a card in my name when we were legally separated?

Your spouse’s actions may constitute credit card fraud. My advice is to contact your card issuer to file a report and find out what steps you need to take to reverse this charge.

Can there be charges brought against my ex for this?

Likely yes. Contact your creditors first.

What if her name was on the card, BUT, we had a verbal agreement that I was going to take over that card, and she would keep the others.

If her name was on the card and she was authorized to make charges in so far as the creditors are concerned there is no fraud or crime. Though her behavior is reprehensible based on your prior verbal agreement.

In order to fairly distribute the debts you can file an action for equitable distribution.