Family Subscription convert to Independent Subscription

I want to break free from a family plan to an independent plan. I have followed the steps to change my email and password. But there is an error stating that the email address is already in use. 

I created a new email account on Gmail and tried using it as my new email address login but again it says email is in use.... But how I just created it in Gmail?

What can I do to make my profile independent without loosing all my music?