Dad's Last Name ~ Nope!

DRIAM7

I will be a single Mom when I deliver my baby, but the father is still around whenever we can actually get along nowadays.  I know he will not stick around long enough to help during trying times, so I already resent him.  He knew when we began dating that I was a stickler for NOT giving a child the father's last name if we were not married.  Now that I am pregnant with HIS child, he thinks it's going to be different.  I do not plan to give the baby his last name, but don't want to push him back further from the minimal contact he will already have, by doing this (not carrying his last name).  How do I break it to him that our child will NOT carry his last name because we will not be married?  Do I even break it to him, or complete the birth certificate later AFTER leaving the hospital and 'sneak' and do it?