I had posted a long reply to this explaining what had happened but it was lost when trying to sort out duplicate posts that had occurred (apparently deleting a duplicate also remove the original).
The critical part was you should change passwords on all accounts to ensure that he does not have access to your accounts. This includes email accounts as well as your Apple account.
Here's how you change the email address (Apple ID) you use for your Apple Account while retaining everything in your account:
1. Go to https://appleid.apple.com and sign in.
2. In the Sign-In and Security section, choose Apple ID.
3. Enter the email address that you want to use as your Apple ID.
4. Choose Change Apple ID.
5. If you changed your Apple ID to a third-party email address, check your email for a verification code, then enter the code. Learn what to do if you didn't get the email. --> If you didn't receive your verification or reset email - Apple Support
6. If you use services like iCloud or Messages to share with friends and colleagues, sign in to those services with your updated Apple ID. --> What to do after you change your Apple ID or password - Apple Support
For more details, read the document: "Change your Apple ID" --> Change your Apple ID - Apple Support
As for the data, you will have to ask him to delete it. There is nothing you can do about that. Your accounts are not actively connected.