To change his email and retain all purchases, follow the steps in the article below.
Note the restrictions in the article.
Apple ID Name Change
What to do after you change your Apple ID or password - Apple Support I suggest doing this before you change your Apple ID or password.
Reference using your address to create a new Apple ID, Apple hasn’t published any guidance for using an address again. Normally, if your e-mail address was associated with an ID in any way, for example as a Reachable at or Rescue e-mail address, then it can't be reused with another Apple ID for approximately one year. I have also seen posts that stated Apple told them there was a 30 day waiting period before the address could be used again. You will need to get another e-mail address to use as your Apple ID or you can try waiting 30 days to see if that works.
Apple ID - create a new
Apple ID – Create
If you create a new account, you can set up Family Sharing with your husband to retain access to all prior purchases.
Family Sharing
Family Sharing - Set up