Big decision

I've been with my significant other for about 11 years. He struggles with alcohol addiction. He's a great man he's a great father but when he's drunk he's a different person. He quit drinking a while ago but recently has taken it up again. I don't know if I can go through all staying with him through that again we have two daughters and we're expecting a boy in July. I'm tired of the abuse I don't want my kids to see that. I just don't know what to do. He's denied several times that this child is even his. I honestly just want to take my kids and run. I'm so overwhelmed and I feel like I'm stuck.