Hi Emmajkav,
It's always best for each individual to have their own Apple ID. You can completely sign out of his Apple ID on your iPhone, and create a new one for yourself. The following link will show you how to sign up for a new Apple ID: How to create a new Apple ID - Apple Support Please note that when you sign out of his Apple ID on your iPhone, you'll no longer have access to any apps or purchases made with that Apple ID, other than what is outlined below.
Once you have your own Apple ID you can still share purchases with each other using the Family Sharing option. Learn more about Family Sharing and how to set it up here: Set up Family Sharing - Apple Support
Good luck!