How do I stop sharing call history between two iPhones?
If you are on the same Apple ID that is going to happen.
You can set up your own Apple ID, including @icloud.com email address for free and then link it with your husband's account for the purchasing of apps, music, etc., using Family Sharing

4 people in my household are on iDevices and each one has their own Apple ID or iCloud address...but it is all linked to one account and we use family sharing.

Just make sure your husband doesn't set it so that he has to "approve" every purchase you make! ;)