Daughter in law is horrible parent

With their 3rd child now and she has yet to become a nurturing mother. My son is the main caregiver and she basically does nothing. I have had it with her, my son is surprisingly the best father I have ever seen. He puts me to shame in that category. His wife is very lazy and used to giving orders. She has a salon and hardly has to work there at all, although she acts like she is very busy with work she is not. She stays on my son’s ass non stop. I have had enough and I’m ready to give her some parenting. Her parents according to her dumped she and her sibs at grandmas everyday, doing this several times a week so they could go to the casino. They were not real gamblers just nickel slot players. I’m close to letting my d in law and her family have it.
She puts every bit of the children’s care on him. It’s like she wants to run him off but that would be the last thing she would do. I have way more money than this bunch of trash all put together. I am at the point where I’m ready to tell her I will spend every dime I have for my son to get full custody.