Correct me if I'm wrong, but with 3 children and another on the way, I assume that YOU are the parent that is at home all the time, while your husband is the one who is off at work, yes?
Your husband very much needs to listen and comprehend what you are going through and how you feel. He also needs to see the situation through your eyes, not his own. I'm sure when he comes home the dog is great and he is the master and everything is hunky-dory, yes?
Well, YOU need to be the Master too!
Put it this way, a dog that would physically stand between myself and my children would have no place in my family or my home with that sort of behaviour. Not only is it an absolute bloody joke to have to deal with, it is a potentially dangerous situation.
Either this dog gets some serious obedience training together with a massive change of how you all deal with his behaviour at home, or you find someone who can do those things.
Once again, all the best.