I need to change my xboxlivefamily.com email to my new personal email and it won’t even let...

But you can't change the primary email, i've tried many times on my old acct that uses the old @xboxlivefamily.com. so am not sure how they could've changed my email without it also notifying me as well.

The @xboxlivefamily.com is the Microsoft Account assigned to an account when created through the Family Plan. It is not a real email so if you change the Microsoft Account name it will require an actual email at that time.

@xboxlivefamily.com is only a temporary Microsoft Account. You can create your child an email of their own using the outlook.com email and change it to that but at this time that is the only option.

I created a brand new email and logged out of the email before logging into xbox.com with my original email attached to my account. I went to my xbox to change the email and it gives me that code and wont let me change my email. If you make a hotmail or
live email does it create a gamertag for the email even if you dont sign into xbox.com?

I think the problem is that my xbox account was originally a family account and it will not allow me to remove the xboxlivefamily.com email.

you would go to outlook.com and sign in with the email and password and it would bring up the emails for you.