new mom and step child

I feel like a bad person and don't know how to handle things. I have a 3 month old and my boyfriend has a 3 year old, I knew the girl since she was 1 and she stayed over and we take her out for activities and spend holidays with her. I even buy her stuff with my own money. But when I got pregnant I was going to school full time and was tired. Then the baby came and I'm sorry I'm EXHAUSTED it's so much work I take care of my daughter about 25 hours a day, my boyfriend literally only gives her a bath and complains and gets frustrated when I ask him to watch her at night so I can sleep for a few like screaming mad when she cries, so I do it alone. But he wants to take full custody of his daughter and I love her but I dont think I can raise two kids when I only take care of mine. My boyfriend works 7 days a week sometimes about 12 hours a day then he likes to go out party....and his daughter does not listen to anyone and when I tell her to stop or something he gets mad and yells. She was literally jumping on the bed while my daughter way laying there sleeping and almost stepped on her head. Like I don't want to do it honestly I know the children have nothing to do with it but he says he likes his daughter more and my baby is a crybaby.