I have not had this kind of experience (yet), very sorry to hear you are going through this. The apparent injustice of it is effing galling! I am sitting here angry for you! But, I think you are getting some great advice here. I am a firm believer that the leopard does not change its spots - it is extremely unlikely that he will somehow transition to a happy life from here without recovery.
One of the things that has helped me immensely in dealing with my own anger has been the realization that while I was present for it, the bad behavior was not about me. It angered me that she would treat me like she did - it made me crazy, but I was finally able to let it go when I one day realized IT WAS NEVER ABOUT ME. The drama that she stirred up around me, and often drew me into, was just her weird way for her to justify what SHE wanted to do, i.e. drink. Nothing like drama to justify escape and self-medication, and I constantly obliged. She would do something annoying or stupid, I would cause a fuss, which made it ok for her to drink.
I also believe that most of my anger was (and is) really at myself for allowing her to treat me that way, and that my misguided attempts to help her, and continue, which I told myself was the right thing and was due to my altruistic good nature. But I suspect now that instead of doing the right thing, I was trying to avoid confronting my own fears as to what this would mean to my life, and denial that this fate could befall me. Once I saw the drama for what it was - a conscious or unconscious way for her to justify bad behavior, I was able to shift away from being angry at her, and confront my own inability to break free of it. Now that is not to say that letting go of my anger somehow fixed anything or let her off the hook. It just made it clearer to me what was going on, and why it was unacceptable and toxic. It allowed me to embrace the idea that I still do care about her, I just can't abide the alcoholism. This caused me to shift to a profound grief at the loss of the marriage I thought I had, and of course, precious time.
However, it is still not over for me. We are separated, and going to counseling together, and I still find myself getting drawn into arguments, getting miffed at some some passive-aggressive curve ball she throws my way, and still wondering if our marriage can be salvaged. As I write this, I can't help but wonder if I really believe that is possible, or if I am still trying to be the good husband, avoiding the conflict.
As I have only learned myself recently - we all have a part to play. Mine was stuffing that anger at myself. In some weird way, I felt that my anger was somehow necessary to explain why my marriage was failing, that I felt unhappy and unfulfilled in the relationship. I heard the unspoken entreaties from our families to make it work, give it a chance - I tried to do the right thing, support her, wanting to believe her when she promised she was done drinking this time, because the alternative was unthinkable. I thought I was being a patient husband, but what I was doing was patting myself on the back for being a good guy, while unwittingly teaching her to lie to me and tell me what I wanted to hear, because that is what brought (temporary) peace. In the moment, I am sure she may have felt sincere in wanting to stop, but not for herself, but to keep our marriage together. By avoiding confrontation, not setting boundaries, not setting consequences, not enforcing them, I set myself up. She was just being the scorpion that an alcoholic is, and I was the apparently willing frog.
I have since accepted that I don't need to be angry to justify my feeling that I don't want to be around her, her thoughtless, cruel, and inconsiderate behavior is sufficient for that. Not everyone has seen that side of her, and while some vindication might be nice, I understand I might not get much - how would anyone else know? I would expect that if/when the day comes when we divorce, there will be those that support her in building a new life, and will forgive her (from their comfortable distance) and will hope she is happy. That is what her family and friends are for, after all. I can't expect or want them to shun or abandon her. Some of them might even blame me. So be it. All I know is, I have done my best, fought the good fight with my heart in the right place as much as I possibly could. I didn't always do the right thing, but I sure tried. I see I have made mistakes, but I have always acted in good faith. I don't need anyone else to validate that, I know in my heart it is true. And I hope that can be good enough for me.
We really can't be surprised at his family's behavior - if you think about it, they may well be quite aware of the problem, but are hoping it will just go away. What are they going to do, call him out on Facebook? Of course not! Even if they are so naive as to believe his problems are over, we all know the power of pretending everything is fine. You might be out of that picture, but they still need to interact with him, and unless he's messing up their lives, who can blame them for hoping he will somehow get it together (maybe if they just be nice to him, he'll stop!). Who knows what they are really saying to each other, or whether anyone really believes the fairy tale? And does it matter?