Butterfly, I read your older posts. He first left you shortly after your marriage. Then again for five years. 18 years and he has left at least half a dozen times. You need to get the hint. The marriage was a mistake.
He may have hoped to have a normal future but he just isn't wired for it. He has drank you whole marriage, did drugs and abused you. You don't even know who he really is. Someone who is constantly under the influence is incapable of forming or maintaining a normal relationship. And you are slowly killing yourself over a fantasy. You have ignored the reality of who your husband is for 18 years. He never existed and spiritually your slowly dying.