Hi PW66, welcome back to the community! Thank you for posting.
Sorry to hear about the address being compromised.
Are you looking to get the email address closed down permanently? Or are you hoping for it to be transferred to your account so you can retain access, and change the password?
If the email is a secondary email address of an account your ex partner is the account holder for it would need to be cancelled / deleted by them directly. We would also need their consent before we could request a transfer of the email to your current active account.
Let us know how you are moping to proceed with this so we can offer support!
Following this, we will need to send you a PM to confirm a few account details and pass security.
All the best!
Molly