Advice please!

So my baby's dad and I are not together we haven't been since I found out I was pregneat but whatever that's beside the point. We'll I'm seeing this new guy and he's seriously driving me crazy he is always saying "ours" as in mine and his kid! This isn't his child! It's my exs baby. He's not getting the concept of when I say stop it's not your baby. So now he's got this thing that he's adoption him jus because his dad isn't on the birth certificat. I'm going crazy. Help please