So sorry that your daughter-in-law is behaving so bizarrely. Granted she has been through a lot, but her partner needs her NOW. It seems she wants to do everything to completely escape from her sad realities of life. There really isn't anything you can do. She could really benefit from grief therapy or just talking to someone about life and loss. She has to be the one to seek it out, but it almost seems in the interim, she is almost neglecting your son given his serious condition. I hope there is some resolve shortly.