It has to be exhausting for you, and confusing, and discouraging.
Personally, my instinct for your situation is that you continue what you are doing: going to Al-Anon and not yet making any major decisions.
You said "I'm not far enough in Al-Anon yet....." This implies to me you maybe have less than a year or so in the program? Living with alcoholism creates such distorted thinking and irrational behaviors and automatic defensive responses in us that it takes us a significant amount of time to find our center and know what we want and who we are again.
I am not surprised that your marriage has never been happy, as it has been an alcoholic marriage.
In the years you have been with this man you have planted deep roots, you share 20 years of memory and history and "entanglements" both positive and negative. And it seems to me you would not casually destroy this shared life, and so you are hesitant to bolt just because the happy sober marriage has not yet emerged.
Alcoholics create wreckage. They shatter trust. They leave their loved ones in pieces. And they are themselves in pieces when they finally try to get well.
I don't know how long he has been sober but Post Acute Withdrawal Syndrome is a very predictable passage for an alcoholic in the first three years of sobriety, and for anyone trying to connect with the alcoholic, it feels as miserable as he says he is.
I don't have any advice. I just want you to know that a hurricane of addiction has destroyed your life and his, and it will take some time before you feel your marriage is safe harbor, if ever.
You have invested 20 years. If you stayed out of fear and never knew him or liked him, then there may be little to salvage.
But if you think you stayed because something in you wants to be with this man, and if that something in you still has life enough to continue Al-Anon, support his AA life however that unfolds for him, and work with a counselor to find out who you are now, in a sober marriage, then whatever choice is finally made about your marriage will be with deepest conviction and a sense of peace. It will not be made out of anger, frustration, resentment. You will feel calm, I hope, and take a look at things and say, "I'm done," should you decide to divorce.
As much as I personally wish that those who live with active addicts would leave them--temporarily at least-- so the addict's disease has full opportunity to bring him to a miserable bottom with no spouse to blame for his misery (alcoholics always blame someone else but if no one is there, then it might hit them that drinking is the problem).....as much as I usually suggest at least physical separation and minimal contact with active addicts........still, in my heart, I hope that the Promises of Recovery are really true. And that it is possible for marriages to be rebuilt, families to be reunited, and there be role models for others so that recovery is not just an idea in a book.....but is real and actually beautiful.
I miss the addict I am in love with. Last time I saw him he was an arrogant, selfish, blame-deflecting, self-pitying, complete Addict Personality MESS. And I'm not sure if he was clean or not. 15 years clean time, but I'm not so sure what the truth was a year ago when I last spoke to him.
I'd love to be with him, in parallel recovery, to repair our relationship, and be true individuals, not dependent, but committed to growing up side by side.
But that is because of all the men I have ever known, he's the one I would have walked through fire for. So for me, the hard work would have been worth it, to see if we could make a strong and enduring union.
But he's not recovering--clean or not-- and it isn't possible this day.
You may not feel that way about your husband now--the walking through fire part-- and there are many justifiable reasons why.
But you have built a life together and that is probably why you stay for now.
I would not expect any real happiness between you in his first year and your first year of recovery. Maybe not the second year either. There has been so much damage. Both of you are still pretty crazy. (Sorry....but that's what the family disease does).
But perhaps your long life together, 20 years, is reason enough for you both to commit to no major changes and to pursuing individual treatment for at minimum a full year. As long as there is no ongoing abuse. This includes verbal violence.
Whatever happens, you will emerge stronger and deeper.