In all honesty he won't quit until he is really ready to quit and has a realisation about what he is doing to himself. What he is doing to his family, friends and those about him are irrelevant. He has to be the one to do it.
I speak from experience.
Until 17 days ago I drank a 1/2 bottle of vodka every night and more at the weekend. This had been going on almost solidly for the last 20 yrs plus. My first grandson arrived almost a year ago this week and I tried to stop at the start of last year for his/her sake. It didn't work.
About a month ago I realised my health was getting worse (no shit Sherlock!!!) so I joined a Facebook group and read a book that was suggested in the group.
That was a life changer!
At the same time I made a plan. I would quit on a certain day and take the rest of the week off work as annual leave to cope with the withdrawal symptoms. In the weeks leading up to this date I would cut back to make things, hopefully, easier. That didn't work. In those 2 weeks I probably drank more.
But...
The message in the book I read got through. I had my last drink on the Sunday night as planned and went to work the next day feeling the same hungover way I had done for years. On the way home I made the decision NOT to pop into Sainsburys on the way home. The night went great. I didn't want to drink. A caveat here. I did have some alcohol left in the house just in case I ended up climbing the walls. Didn't need it and 17 days later it's still there!
Now I might have been lucky this time as my enforced abstinence produced no withdrawal symptoms and I've not had any inclination to touch alcohol at all. Last weekend I was away on a football weekend with the lads in a foreign country and despite the beer flowing all around I never touched a drop.
The only explanation I can give is that reading the book shone a light into my subconscious that made me ready.
Not sure this is really helpful to your friend but it really comes down to her husband being ready. No amount of badgering or cajoling will really work.
Wish her good luck from me.