This is one of the reasons I recommend spending less than $20/yr for your own domain and email hosting. You'll then own the domain and you'll never have to change your email address. No one can ever force you to give it up (except maybe a court order). There is no advertising, not as much spam, etc, etc, etc. It always amazes me that people use the email addresses provided by their ISPs.

If you want to keep your email address, you'll have to continue the service. Man that is an expensive email account

If I were in your situation, I would choose to pay for 1-6 months of service depending on how important the email address is and then notify every single person who sends you email on the old address of your new email address. Even if you're spending $100/mo on internet access, that is still probably less costly than losing a future customer and/or sale.