Caligrandma
Very tough situation. On one level you want to see if you can rectify, on the other level it will be turned on you too. On another level it's simply very bad and evil behaviour to disown a parent and to ignore it seems easiest although what does ignoring evil behaviour say about ourselves. Very tricky. Chances are very high that saying anything ( including calling out evil behaviour) is going to jeopardize GD relationship with you. I would talk to your son. Sympathize with this dreadful D behaviour and ask is there anything he would like you to do. My heart goes out to his kind of suffering. There are no words for this selfish evil behaviour that people feel entitled to these days. I'm sure your son was a loving devoted generous father. I'm sure of it. I would reach out to your son and offer support and ask him what he would like you to do. This is not going to change anytime soon. I wish I could tell these 20 and 30 year olds what the xxxx are they doing. Incredibly narcissistic of the GD. Support your son I say. Be on the side of Christianity rather than the side of evil.
Sorry but I think this comment is incredibly unkind. 'Evil', saying 'be on the side of Christianity' and then saying some of the things you have said. Where is your compassion? We don't know exactly what has happened and can't speculate, offering support is one thing but suggesting that a person is evil is not acceptable.