What should i do? me or the kids?

I am married to the father of my two daughters and he is not nice to me. he always talks down to me and calls me stupid and out of my name when he cant find something or when he gets mad. he has hit me before too, but always says hes not gonna do it again. i dont know what to do because im tired of the way he treats me, but he treats the girls wonderful and is really nice to them. i worry though because everytime we get into it he says he is going to leave me with the kids and i dont want to raise 2 kids alone and i dont want them to grow up without a father. I feel like im in between a rock and a hard place. I cook, clean, and go to college and its like i never do enough and everything that goes wrong is my fault. I always want to cry, but when i cry he tells me im weak and to stop crying. he always admits he knows the things he does are wrong but he keeps doing them. he even told me to kill myself before. i dont understand why he treats me like this. usually people like me because im very nice, respectful,smart and im pretty ( im not just saying that). people stop me all the time and tell me i should be a model and all my teachers and counselors tell me how proud they are of me and speak so nicely of me to others and i cant understand why he doesnt see me like that. i know i could have any guy i wanted, but he is making me hate all men. What do i do? stay to keep the kids happy or leave to make me happy?