Should my child have his last name?

Norma

My ex lover & I split up a week ago. Less then 4 days later he fucks his ex/ baby momma and asks them to move back in with him.. long story short, I'm a new mom... its all so different & terrifying, specially cuz imma be doing this mostly alone. He has agreed to help out with money and stuff but that's about it. I greatly appreciate it but I feel its his responsibility since I didn't want a baby anymore after 4 months of TTC while we were together & he finished inside me regardless of my wishes. Although the baby was made while we still loved each other I feel like he shouldn't have kept trying to get me pregnant under the false pretenses of "loving" me. Therefore considering all these things on top of his drug addictions & his baby momma drama.. I wanna keep my baby from taking on his last name. He'll be outside the delivery room while I give birth but I dont want his last name for my kids.. . too much bullshit attached to that last name.