I am glad you offered up the "join the family at Christmas" option. If she comes, just be yourself and enjoy the day w/your children. Christmas is about the children and the new memories that you are making w/them. If she doesn't come, then let it be. If the children ask where she is you can be honest and say, she may have had other plans.
As for pressure on doing well at Christmas...no one is perfect and it can be a very stressful time of the year. Try to keep things simple. You don't have to go over board and jump through hoops. Your children will be happy w/whatever you plan for them because they are at home, with gifts under the tree and spending the time with you.
Just be yourself.
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.
