Baby having mothers last name

So me and my baby's father haven't been together throughout my pregnancy. He hasn't done one thing for my child literally nothing. He's spent all of my pregnancy dealing with a felony charge (that he intentionally skips court for) he received on the opposite side of the country from us. His mother found it appropriate and  had the nerve to tell me that I'm a "horrible" "selfish" mother for giving my child my last name. Apparently I'm embarrassing my son and not "thinking of his feelings" hours after I gave birth. Personally I see nothing wrong with giving the child that I support on my own my last name but that's just me.