Some things just need time and i suspect that after the divorce things might settle in a bit more. She may have trouble seperating her husband from you right now. It sounds like everyone's feelings are very raw and pushing right now can sometimes push people further away. Whether she is fair or not is hard to tell without hearing her side of the story.
I just think take some time, let things heal, and then listen to her because she is the one who does ultimately decide until the courts do. Dont give her any ammunition against you before that time. Maybe even be the bigger person and send her a Christmas card - tell her you understand that things are strained right now but hope that the wounds will heal in time. You are older and wiser and you may find there will come a time that she will need you in your grandchildrens lives.