Help! Lol

So I'm 19 weeks and 5 days and the father and I aren't together. At first he didn't want me to keep him and I decided to. We didn't talk for months after we found out and now he's more involved. Mt question is...he wants our son to have his last name. Do I allow someone who was so rude to me and originally didn't want our son to have his last name or give him mine???? I'm stuck.