How to deal with moody abusive husband?

My husband never seems to be happy unless he's drinking, smoking, or has exersized. When he has had none of this, usually in the morning, he is a trainwreck. He is very irritable and very mean. He says mean things to me and lashes out on me. After he has relief through one of the above, he is happy-go-lucky and thinks I should be too. I am at my wits end! He calls me fat, stupid, and swears at me. This morning for the first time he punched me very hard in the shoulder, which is still very sore. He did this out of anger, there was no joking around. I am not the type of girl to put up with abuse. His friends are always over (who have no families or girlfriends.. drink and smoke) and his priorities dont involve his family first. I am most concerned for the well being of our three very young children. Sadly enough, I feel like the only way he's going to have a reality check is not by me telling him about how I feel... since that has never worked, but by leaving him. If anyone can give me some kind of advice it would be appreciated. If you want to belittle me and judge me, dont bother.. I already get enough of that so I wont listen. When he comes home, Im going to suggest for him to see a psychotherapist. If he declines, I plan on seperating from him. Does this sound like a good idea? I really just dont know what to do. He makes me feel crazy!