Turbo tax keeps asking about my ex-spouse. We have no dependents together and no interaction of any kind, legal or otherwise. Why does turbo tax ask about him???

You are correct that TurboTax should not be asking about your ex-spouse if you indicated you are filing as Single. 

Go to the Personal Info section and review your entries there.

Or, click this link for info on How to Clear and Start Over. 

This link provides detail on What is My Filing Status?

You are probably in the wrong account.  Did you set up your own new account last year to file divorced?

If you used Turbo Tax for 2018 you should have started a brand new account for 2019 and not transfer from 2018.  You can not remove a spouse or switch the order of names.

Online is only good for 1 return.  But you can use the same email address for 5 accounts.   How to start another return in the Online version  

https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-start-another-return-in-turbotax-online/00/25596

Divorced FAQ

https://ttlc.intuit.com/community/family/help/what-if-i-was-divorced/00/25830

Start a new account. Removing a spouse is not recommended

https://ttlc.intuit.com/community/family/help/how-do-i-remove-a-former-spouse-from-my-return/00/27202

Getting Divorced article

https://turbotax.intuit.com/tax-tips/marriage/getting-divorced/L20NC66cf