Why do you feel he needs to know what's going on in your head OP? Once you've decided what's going to happen, ie, if you're planning on leaving, just get yourself organised and a place to move to, pack yours and the kids things, and leave, preferably when he's not there, if at all possible. You don't even have to leave him a note if you don't want to. Let him suffer and squirm until eventually he has to admit to people that he doesn't know where you are, and that you seem to have left him and taken the children with you.
You seem to be all over the place with your thoughts, so can I suggest that you just focus on getting out of there OP? Don't worry about what will, or won't happen with your boys once you've left. What will be, will be, and you WILL deal with it, but it simply has to be better than what's happening to you, and in front of them right now. Kids really DO take on board the things happening around them you know. I can see that your youngest is 3, but can't seem to find the age of the other one. However, I CAN tell you, that I was brought up in a very similar home to the one that you describe growing up in, ie walking on eggshells, so as not to upset my Father, and from the age of 4 years old, I remember VERY clearly what was going on in the marital home, and the way my Father was treating my wonderful Mum! I remember the nightmares I had to this day, of my Father swinging my Mum against the cabinet in our dining room, and her head flying off!! This was on repeat for years, and I was obviously terrified that at some point he would break, and kill her!! Times she tried to leave him, but got talked into going back, as I've told you previously, but the fact is, we were ALL miserable, including my Father!
Do you really see Christmas Day being special, while you're still with this man? If so, I think you're kidding yourself, and the likelihood is, that it will be the straw that breaks the camel's back, and you will end up having to leave, possibly there and then. So, do yourself and your kids a favour, and stop messing around, just get out of there, NOW!!