So angry with myself

My baby girl is almost 6 weeks old and right before I gave birth I decided to change my mind and give her her fathers last name instead of mine. That was such a mistake. For some reason I thought maybe he’d change after seeing her but he’s still the same toxic manipulative abusive person he has been to me the past four years. I wish I could go back and just give her my last name like I had planned on doing from day 1. Somehow he convinced me to let her have his. He never wants to come around hasn’t bought her a single thing. I still give him opportunities to come see her even though the handful of times he has come to see her he doesn’t do anything I had to ask him to hold her. I told him if he didn’t wanna be around to just sign her over so I can change her name to mine and he went off the deep end on me telling me he was going to take her from me, literally told me he would kick in my door and kidnap her from me. I’m such an idiot for having a baby with such a horrible person