He is under the influence, he is dead, spiritually, emotionally, physically, and mentally.
For me, once I made the switch between having a relationship with a person to having a relationship with an addiction things got a whole lot easier.
The man you love, loved, etc.... is not in the picture, when he is somewhat lucid, all that speaks to him is his next drink, next fix, next pleasure, his next mind numb. He is incapable of reasoning, his addiction is in control of his life, his actions and the way he lives his life are completely under the control of his addicted brain. He is lost, you are simply a way to his next drink, when you become anything else, you are just in the way.
Your relationship with him is controlled by his need to feed his addiction, that is the cold hard, but simple truth about the situation we find ourselves in. There is very little that makes sense or is believable in addiction. It is chaos and it will destroy you if you do not get away.