My vote is for option 3 - do nothing other than what you have agreed to.
She also said that the children should come to me for Christmas and she would come across, as she had last year, and stay for Christmas lunch.
Seems she is clear about what she wants, why muddy waters with Mr B at the lunch table? I reckon she likes the tradition of 'your' family at lunch in your place. Now, if you should have a lady friend present too, maybe she may not suggest this next year. If you really have moved on, you would most likely have new interests in your life, not pander to the interests in her life.
Slowly
