If there is a divorce, everyone won't get to share the daughter on the calendar date of her birthday. However, you can celebrate her birthday any day of the year. If there is a divorce, she will be having two birthday celebrations, two Chistmastimes, two of everything. Understandbly, I hate it for you, however, your W is the one who needs to learn what divorce looks like.
You must learn to tell your W "no"! Sometimes you just have to bluntly say you think under the circumstances, you had rather she didn't come. This is what separation involves.
When a man is scared of losing his W and starts letting her do whatever she wants, it kills her attraction. That is just how women are wired. She will test the H to see how far she can push him, but secretly, she is hoping he will be man enough to stop her from being a bully. Your W will never you tell you this......and perhaps no other woman will, but I'll tell you it is the truth.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!