iI would explode. Whatever money I had would go to getting a divorce with custody primarily with me. I feel so sorry for your daughter, watching a tennis match at an age when she can not understand what is going on. I recall how I felt as a young kid. My mom let us celebrate our birthdays in exchange for our silence towards our JW relatives. It was weird having secrets about normal things. Knowing that I was free to celebrate but must pretend that I did not did bad things to my head. I was too young to understand that all members of a family do not share beliefs. My mother somehow made me feel ashamed. They didn't have to hide their JW bs.
It is not the actual event, a birthday party. The underlying theme of deceit and shame continues to this day. Altho I've been out for decades, and way out in my sister's and doctor's estimation, I still have trouble asserting myself. My people pleasing ways embarass me.
Yet I know many Jewish-Christian marriages from being in NY. I don't sense shame there but they respect each other very much. The problem I see is that the Witnesses are relentless. Grey does not exist for them. What five year old is sophisticated enough to understand color theory?
Your wife's inconsistency even makes it worse, rather than better. Of course, I don't believe in joint custody for divorced couples. If you could get along to do it properly, you would not need a divorce. This must hurt b/c it is about your daughter and not just you.