Just playing devil's advocate here:
1) Relationships involve the 2 people in a relationship, not their parents.
2) When parents get involved in their children's relationships, they naturally do the opposite of what they're told. That can't be helpful.
3) As an alcoholic (recovered or not), shouldn't she be more understanding of her son's illness?
4) She can't speak truth that hasn't happened. She may know her son better than anyone and know alcoholism as well as anyone, but nobody can predict the future.
Just something to think about..