You're already doing one of the most important things you can do for your husband: You are trying to help him, and you are loving him in spite of his problems.
I know these last few years have been very difficult for you (as the rest of your letter indicates), but God has given you strength in the midst of them–and He will continue to do so. He also has answered your prayers for your husband by bringing him to Christ and breaking the terrible hold that drugs had on him–and He will continue to answer your prayers. The Bible's promise is true: "The prayer of a righteous man (or woman) is powerful and effective" (James 5:16).
True love means loving someone in spite of their faults and difficulties–which is the way God loves us. Let your husband know repeatedly that you love him, and ask God to give you the patience and wisdom you will need to help him. But most of all, remind him of God's constant love for him–a love so great that Jesus Christ was willing to die on the cross for him.
Seek practical help also for your husband, both through your doctor and through community agencies that may be able to help him deal with his disabilities. In addition, you know from experience how terrible drugs can be. Ask God to open ways for you and your husband to warn others of the dangers and point them to Christ.