What Is The Best Thing To Do Here?

My wife saved money to take our 3yr to Disneyland for 2weeks. However, I told her let’s wait till Christmas when my other daughter with my EX is out of school for Christmas break. However, my wife says we can’t wait ‘cause she wants to take our 3yr there for his 3rd BD and she already paid for everything and she will lose 20% of it if she cancels it now. I talked to my ex to let her come before Christmas for 1week and she refuses it. What to do? BTW my daughter is 13yrs never been to Disneyland a day in her life before and she really wants to go but my bitter EX won’t let her till Christmas..