Sephra, I am so sorry. I understand that kind of pain very well. Your husband is not well, it doesn't sound like. He is so wound up in his son that it seems he doesn't even know where his own boundaries begin and end. That is sad, but it doesn't seem to be something anyone can do anything about but him--and he doesn't believe he has a problem, right?
When I was married the first time, my now ex-husband had an affair and filed for divorce. He seemed very cold and hard about the whole thing, too. It was very final and unequivocal. But I survived and even learned so very much through that whole time. I know that you will, too!
And I have to say: You are more than enough!!
Please take good care of yourself. Under the circumstances, I would also consult an attorney at your earliest possible convenience for your own protection. I hate that divorce seems so adversarial, but I hope you will believe that you deserve to have someone fighting for you!