Protect your assets and make a list of the bank accounts you are the owner, the co-owner and the agent.
For your individual accounts, you have nothing to fear. Your individual accounts are managed autonomously, regardless of your matrimonial regime, and only work with your signature and under your own responsibility. If your ex-partner has a power of attorney over your accounts, revoke it as soon as possible.
If you have a joint current account, the best solution is to close it. Before closing it, keep in mind that the joint account is often used to pay domestic expenses and has direct debits and/or standing orders to pay recurring monthly bills.
You have to follow the same procedures for your bank cards and your assets in safe deposit box.