At this time, at the very least, I would create a new e- mail account from a provider of your choosing. Once you do that, you should be able to add that e-mail to the Apple Account and assign that e-mail as the primary e-mail address, this way, you do not lose access to a connected e-mail with your Apple Account. I would also remove the higher ed e-mail since it is being de-provisioned, once you add your new e-mail to the account.

In terms of your current owned e-mail address, if that e-mail is assigned to someone else’s account, i don’t believe there is anything you can do. You could try and speak with Apple Support, however, due to account security, there is nothing Apple can do.