There is a lot of misinformation, as well as down right prejudice, peddled on here about "alcoholism", OP.
The truth is, of course, that there are many ways people can have difficulty relationships with alcohol;; that not everyone who drinks slightly more than some posters here would is an "alcoholic"; and that it's not possible for anyone to diagnose this guy as anything without even meeting him, just hearing about this one thing he has done.
I am several years sober, having had a destructive relationship with alcohol in the past, and ideally I don't think anyone would drink - it harms more than it benefits.
But nonetheless I don't see any reason to assume your husband is on the brink of descending into alcoholic madness here. Plenty of people DO drink a bottle of spirits of the course of a evening - you say it usually lasts him two evenings, so it is not as if he has increased his drinking that drastically.
I sincerely doubt it has given him liver failure. If it had, I promise you would know.
I do think he was self-medicating on this occasion, which is a really common reason for alcohol use/abuse, and obviously less than ideal.
The most worrying thing for me is that your husband is suffering from depression that is bringing him down to this extent. And there were a couple of other red flags for me in your posts (forgive me if I am wrong about these).
- You put the children to bed and stayed upstairs with them. Leaving your husband downstairs on his own all evening. Is this a regular occurrence? It is not ideal for cohabiting partners to be detached from each other to this extent, but especially when your husband is suffering with his mental health - doesn't he need company, cuddles, care? I am not trying to blame you in any way - no doubt you were busy with the kids, not just leaving him to it out of indifference. But could the bedtime routine be adjusted so that you and he get quality time together? This is in my opinion essential for mental health and the health of the relationship.
- You describe a self employed grafter who even works weekends, who even feels obligated to go to work when he must feel horribly unwell (mentally and physically). How much strain is this work pressure putting on an already unwell man, and can it be adjusted?
These were my initial thoughts. Alcohol misuse, whether regular or occasional, is frequently a symptom rather than the disease itself. You have to treat the disease, not the symptoms. Get to the root of his depression. And sometimes meds alone just aren't enough. Sometimes we need to step back, take stock of our lives and make changes.
Best of luck.