Why do I put up with him?

My husband came in tonight glued to the TV. Last night he stayed out till 3:30 this morning. I cooked dinner for the kids then cooked his dinner because he didn't want what they were having. Then I had to get the baby ready for bed. While I was making his dinner, our daughter wanted to show me what she did at school today but I couldn't look cause I was busy so I told her to show him. She came back mopping so I cause he told her he's busy watching TV. This is a guy that comes every night when they aresleeping. The baby starts crying and I have to drop whatever I'm doing to attend to her. I turn on the light in the room to pick up the baby and he starts cussing, I mean very colorful language. Thank GOD the kids were sleeping. What am I gonna do . I have 3 kids and its killing me. I dont want our son to think its ok to treat women the he treats me, and I dont want our daughter to think its ok to let any man treat them the way he treats me. I think I should take them and leave. Our oldest daughter is not mine biologically but if I'm leaving I want her to come and think he would allow me to take care of her. Please help me. I dont know what else to do.