Personally, I would still try counseling. Just because he is not talking and speaking up does not mean he is not listening or getting anything out of it. In time he might just surprise you with speaking up. And if he can hear your feelings and story, maybe it can help him come to terms with it all. I have been to a few counselors and some are better than others, and some we just click with better than others. I would keep trying counselors until one feels right. It is worth a shot IMO.
On a separate note, your post brought tears to my eyes because I am living in a mess with AH (different but still similar) and I have an 8 year old, loving, sensitive, energetic son and I fear what you are going through. My son adores his daddy, and altho AH has serious issues, he is loving to his son and tries in his limited way to be there for him. But you can't shield your kids from all the chaos, and that is what scares me. I'm finally taking some steps to move on and out of this. It will be a few months though before anything is really started officially, and gee, a lot can go on in 3 months or so.
You know, we do the best that we can with the resources we have at the time. I hope and pray that your son will someday see you as the rock you apparently have been for him through the years. Take care.