My no-contact ex still has my checking account linked to his Amex and is using it to pay his balance

I just went through a messy breakup in December, which resulted in me filing a restraining order against him. He's blocked on everything and has been respecting the court order, except for this one thing.

Months before our breakup, he added me on to his Amex card, for the purpose of splitting household expenses. I connected my checking account to his card, and for the last few months we were together, the arrangement worked out just fine.

But now, he just paid $500 off his card with my checking account.

I don't have the amex account info, or even a physical card. Should I contact Amex, or my checking account bank? I'm thinking maybe I need to get a new checking account and close that current one?

Thanks