Hi, Rosalba.
How old is your mom? M alcoholic sib lives with my mother. They are the classic enabling/enabled pair. Always have been. We have something similar. My mother would like her 3 children to share her assets after death equally.
Which will give the alcohol dependent sib a chunk of money.
Which he will blow on booze and gambling.
I would say that, sadly, your mom isn't going to change with regard to bro.
I would continue to work on finding ways to heal and find peace about the family of origin. Peace.