If your divorced husband knows your bank account information, it is important to take steps to protect your financial security. Here are some steps you can take:

1. Change passwords: Change the passwords for online access to your bank accounts and consider using strong, unique passwords.
2. Update contact information: Update your contact information, such as your phone number and email address, with your bank to ensure that you receive notifications and alerts in a timely manner.
3. Monitor account activity: Regularly monitor your bank account activity to detect any suspicious transactions or unauthorized access.
4. Report suspicious activity: If you notice any suspicious activity on your bank account, report it immediately to your bank and take appropriate action, such as closing the account and opening a new one.
5. Consider legal action: If you believe that your ex-husband has taken unauthorized access to your bank account, you may consider taking legal action to protect your rights and financial security.
6. Seek professional help: If you are concerned about your financial security, consider seeking the advice of a financial professional or attorney to help you navigate the situation and take appropriate action.

In conclusion, it is important to be proactive in protecting your financial security, especially in situations where your personal information, such as bank account information, may be at risk.