It sounds like your mum is self-destructing. She's probably in a horrible depression after destroying her family/marriage, and feels very guilty and disgusted with herself.
If you run into her again you could say --mum, stop beating yourself up over the divorce and man you went to, and start living again as there are others who still love and miss you.
These words are not enabling the drunk. They're simple love.
It's still her choice at the end of the day to stay a drunk or not--but at least she may begin to forgive herself if she sees others are willing to forgive her.
Sounds like this choice is coming soon if she's almost broke financially.