This is horrible.
I will tell you what I would do. I don't know what you should do or want to do. It sounds like you want to talk to these people. That you believe you will exchange information that will help you feel better.
I wonder.
First, If it was my life, I would not trust this woman. She would distort and lie about anything you say. Nor would I trust whatever tale she told me about what son said.
Second, there is the issue of trust with your son. He may have betrayed and hurt you over and over again, but he is your son. He is an adult. He has the right to control information about him. And you would risk any relationship you would have with him, now and in the future. That is what I think. If it was me I would stay far, far away.
I would however relay the message to my son about the contact and ask him what he wants you to do.
