It's a classic case. He's drinking because he's embarrassed? You embarrassed him by talking to his mate. Therefore it's your fault he's drinking. That's how it goes. It's always someone else's fault. 

Give it a miss. Best not get further involved. There's no hope for him at this stage, or rather... repair to your prie-dieu
 

I'm sorry that you find yourself in this position. 

For a drinker to stop drinking, they have to acknowledge that they have a problem, and they have to want to stop. There is lots of alcoholism on both sides of my family, and widely different outcomes. A paternal uncle drank himself to death at 59 years old. Every year, he stopped drinking for lent, just to prove to the world that he wasn't an alcoholic and could stop if he wanted to. Then on Easter Monday he would go back to the pub and that was him for another year. I believe that he had a death wish for some deep-seated psychological reason. But he knew that ѕυιcιdє is a mortal sin, so he wrongly thought that killing himself slowly over a period of years would absolve him of responsibility. At the end, he endured a lingering, painful death that was brutal to watch.

On the other side, my mother's brother is also an alcoholic. He was hospitalised just before his 40th birthday and told that if he didn't quit immediately he wouldn't see his 41st birthday. He went home, thought it through and decided to quit. That was 30 years ago and he hasn't had a drink since. Even the tragic death of his 13-year old daughter didn't push him back to drink. When he meets people for the first time, if there is socialising of any kind involved he always openly states that he is an alcoholic and therefore he can't drink alcohol. 

The difference between my 2 uncles is that one wanted to live, and one didn't. So a simple, but blunt, question for your wife's friend would be just to ask him if he wants to live or die.

The 1917 Code of Canon Law does not state explicitly that drunkenness is a cause for separation, but drunkenness could fall into one of the mentioned categories.  Canons 1128 through 1130 deal with separation due to adultery.  Canon 1131 deals with the other reasons, and states as follows:

Other reasons for separation:  if one party joins a non-Catholic sect; or educates the offspring as non-Catholics; or leads a criminal and despicable life; or creates great bodily or spiritual danger to the other party; or if through cruelties he or she makes living together too difficult, and other such reasons, which are to the innocent party so many legal causes to leave the guilty party by authority of the Ordinary of the diocese, or also by private authority, if the guilt of the other party is certain beyond doubt, and there is danger in delay.

In all these cases the common life must be restored when the reason for separation ceases; if, however, the separation was pronounced by the bishop for a time, or indefinitely, the innocent party is not obliged to return except when the time specified has elapsed or the bishop gives orders to return.

Is poor decision making grounds for divorce? People with bipolar disorder often make horrifying financial mistakes and many here would be aghast if a man divorced his mentally ill bipolar wife who can't control herself with money. Is the nonviolent alcoholic comparatively different than having a mentally ill spouse?

Are their truly moral grounds for divorcing a non-violent alcoholic spouse whether man or woman who just wishes to drink themselves into a stupor, but is non-violent? Their are many non violent drunks in the world. I am not so sure that their are truly justifiable grounds. We don't know the nuances of the partivlcular situation and that is why only a traditional priest can advice on the matter.

It's fine to indulge in the occasional Cuba Libre or have a beer or Moscato. But the people who drink like that have serious problems health wise and other.

Ruining the family finances? Dying at 45 because of a blackened liver? Those are grounds for divorce, I think, if they don't reform. They need treatment.

Not every drink eventually becomes violent. You are wrong.

This is all pretty academic as usually when a divorce occurs, one or both spouses eventually "remarry." The only reason that wouldn't happen is if one spouse was truly traditional Catholic or couldn't remarry because of children or poor physical appearance. The couple in the story was novus ordo so my prediction that if a divorce occurs, the wife will get bored and "remarry."