Once I was having a conversation with a recovered alcoholic/addict. I have struggled with alcohol a lot longer than I did with drugs, and I asked him how he did it. I told him that I was proud of him. We’ve been friends for a long time, and he really conquered his addictions.
He said that the biggest source of his strength was the love and support of his wife.
You have really struck at the heart of both scientific and sociological debate about addiction: is it a choice or not? Narcotics Anonymous will argue that he is powerless; Rational Recovery will argue that it is nothing more than a voluntary act of one’s own free will.
My opinion: it doesn’t matter. You have no control over his choices.
In my opinion, the best that you can do right now is to hate the addiction and not the person, thoughtfully consider whatever responses you offer concerning his behavior, and try to find peace with yourself.
Good luck. I'm sorry to see you go through this.