MDB,
Welcome and glad you posted. There is nothing wrong with posting on this forum but you might find more support on the Friends & Family site.
Sounds like you have gone through a lot over the last few years, losing your son and then your husband. I am so sorry for both of your losses. I can see that you have tried everything to get your husband some help, but what have you done for yourself? Have you gone to any support groups? Have you tried alanon or any open aa meetings. Or have your reached out to a therapist over both these huge losses in your life?
They say on this forum that you need to put on your oxygen mask first before you can help anyone else. I think you did the right thing about filing for divorce as your husband is lost. You are entitled to move on in life and be happy, and obviously it is not going to happen with him. Its hard when we still love our addicts and would do anything for them to get well, but eventually we need to take ownership of our own life.
Divorce takes a long time. Continue with what you are doing. He knows what he needs to do, grow up, sober up and work a program. Maybe, just maybe this will be his wake up call and get some help for himself, but sobriety is a one man game. You can not do this for him.
Education is power, read all over this forum, and realize that this disease is progressive, and it will get worse, but understand he no longer needs to take you down with him.
Hugs my friend, you will be ok!!