My sister was in a relationship with a man like this for 2yrs. And anything that happened that meant 'commitment' made him want to end the relationship. I think they broke up twice. (both times for 24hrs)
To the point, no matter how hard you try they won't give in.
So I think it is best you let him go.
But regardless of what he wants, he did help make a baby with you. Even if he doesn't do anything, I think his name should be on the certificate.
Otherwise good luck and congratulations. You are a great mum and will be a beautiful little family.