How to get myself and our son out of the "firing range"

It's my 1st time posting here and I guess this is as much of a vent as anything.....but any tips on how to keep myself and our 3 year old son out of the way of my husbands anger would be very helpful. My husband has ADD. He takes all his stress and frustration out on us every day. I think about ending this marriage every day when the three of us are together and the stress is killing me. I can't wait for my husband to leave for work so that we can have some peace in the few minutes before I bring my son to daycare and I go to work. He is so irritated by my and my son's behavior that he yells at us from the minute we get up until our son goes to bed at night...

When I pull up to the house I can hear him or my son yelling or crying before I even get into the house. I don't want to go in some days but I feel the need to protect our son. Dinner is a nightmare every night. My husband yells and threatens my son to make him to eat. My thoughts are that he will eat when he's hungry and stop when he's full, if he doesn't eat enough he'll be hungry in the morning, lesson learned with no threats. He tries to talk about serious subjects with me during dinner and my son interrupts all the time and gets himself sent to bed or spanked. I have suggested that he save those thoughts until after our son goes to bed so that we can discuss them more easily. If I try to interfere the anger gets turned on me also and we have a huge blow out in front of our child...again.

My husbands ideas on discipline are totally different than mine. He feels yelling, threats, and physical reprimands are the way to deal with a "bratty" child like ours...I feel our child is a typical 3 year old and needs to be taught what is expected of him and needs firm boundaries. I have found that natural consequences tend to be the best teacher and employ them whenever possible. I feel expecting a child of that age to ask "how high" ever time he is commanded to jump is unrealistic..(he literally screams this at our child "when I say jump, you say how high" "NOW!!!") Even when playing with our son, wrestling tickling etc...he doesn't stop when our son asks him to, he keeps going until our son is crying or screaming.

He pushes, slaps, shoves, grabs our son by the face and yells at him. He feels these are the things our bratty son deserves. My son "makes" him do it. I "make" him yell by voicing my opinion of this behavior...The other day  he said "Why don't I just spank you and get it over with, it's what you want and it will make me feel a whole lot better...."

I am exhausted from trying to keep everything together. I am tired of tiptoeing around and running interference between him and our son trying not to make him mad....I try to use natural consequences with my husbands ADD behavior also and let him deal with the results, but sometimes have to interfere because his forgetfulness if affecting me. Like when he's late picking up our son and I get spoken to by the daycare provider about it (she's afraid to speak to him because he gets so defensive). Or when he leaves our sons coat and boots somewhere and I don't have them when we need them, or leaves dangerous thing like knives and medication within our sons reach, etc....

He's been going to a counselor who has experience with ADD, sporadically, but he feels as he does with all councilors that she's just in it for the money and isn't offering any eral solutions for him....he isn't a good candidate for medication due to his obesity, high blood pressure and diabetes.....he does take and anti depressant also...he always tells me that the counselor says it "takes two" to create a problem and that I should think about how I am contributing to these issues (which I do all the time), but contrary to his belief, I do not "make" him react the way he does that is under (or not ) under his control....

Anyway I just wanted to tell someone....I realize that no one can really help me help him, he has to help himself. I just don't see it happening and I'm exhausted and sad that this is the way we have to live if we're going to be together....I don't know if we can be together and my son loves his Dad and is going to be devastated if we are not. The life I thought we were going to have does not exist.