If your wife asks to join you and your family for Christmas, I would consider it. Why? Christmas is a time for families to be together, it is a time for new beginnings and maybe, just maybe being together in a family setting may give her something to think about. It also would give you the opportunity to show her that you are the best (prize) and when she walks away, she will have good memories of the day and hopefully those memories will stay w/her throughout her journey.
Saying no may give her the impression that you are punishing her for the choices she has made. I, personally, do not see her joining in on Christmas as cake eating. Now, if this was something she requested for every family event, then maybe I would.
Just my two cents.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
