Hello, I am Rafael. Thanks for asking your question - I'm here to support you. (Information posted here is not private or confidential but public).
I am very sorry to know about this frustrating and serious reality you described in your message.
What you depict shows a person presenting very serious mental and behavioral issues, for sure severe personality problems-disorders leading to very abusive life style, which does not only affects herself but those around her. She is an adult, then this is not about an isolated episode of a teenager, but about an adult mother and wife, who does present chronic abusive patterns, using, abusing, neglecting and manipulating others as much as possible.
I have to say that this situation seems truly hopeless and would only tend to get worse with time, unless those other adults involved make radical changes. The first person who needs to face reality, confront any abusive and unacceptable behaviors and start taking good care of himself, ending any form of further enabling is your son. Anybody, who does fuel her serious distortions and abuse, would just perpetuate them, making things worse and impossible for any improvement to happen.
All the things you said you have tried, do show how out of fear of not having access to your grandchildren, you have been enabling her abuse and disorders too, and again, that does not help but is the very worst way to deepen this nightmare with all the abuse it presents, specially for the real helpless victims here, your grandchildren.
If your son truly loves and cares about her, then he needs to start taking concrete actions to support her rehabilitation process from all these serious disorders and the end of any form of abuse instead of enabling them more and more with a codependent approach. obviously this would not be easy but would create huge crisis, but they would be necessary and constructive ones, since leading to the need of further abuse and the beginning of her rehabilitation process.
Yes, your grandchildren are being openly exposed to serious abuse and neglect because of it, and that's unacceptable. Your son as the parent needs to take full responsibility for the role he plays in their lives, and look for professional psychotherapy / counseling support to work on rehabilitating from codependency and working on taking good care of himself, children and ending any form or enabling of her abuse and dysfunctions. I am not saying that all these necessary changes would easily resolve all these serious issues, because they would not, but they would allow him to start working on taking truly and responsible good care of himself and his children. He needs to afford the impact and consequences from such tough work, and I think it is necessary and worthy, since he would be setting his priorities and ensuring his children's well-being, his own health and offering the best support possible to his wife. Obviously, if she does not chooses to do the same, look for essential psychological treatment and commits to her rehabilitation process, her situation would not improve and the marital -family relationships would vanish, if he does his job, once it would be impossible for them to live together when one holds full accountability for his own choices and actions and the responsibility of raising his children in acceptable ways, while the mother does the opposite,
Again, it is about assessing reality, the pros and cons of the current situation, and choosing what he is truly willing to afford or not, getting essential professional counseling support to work on it, and hoping for the best, XXXXX XXXXX a realistic and assertive approach, aware that if she chooses to stay the same avoiding responsibility and engaging n her rehabilitation, it would be impossible for her to take good care of herself, and to play any healthy role in their marriage and children's lives. This is not nice news but seems to be reality, and the sooner you face it and start working on it with necessary professional support, the better your chances for rehabilitation, and to protect the children, offering her a chance to do the same, something she is the only one with the power to do so, but at least, would not have the systematic reinforcement-enabling from any of you, and that's a lot.
Does it make sense?