I'm with Divine. I'm one of the invited exes, but not to everything nor would I want that. My adult nephew has an ex wife that is close with his second wife. But neither situation occured overnight. The nephew and his wife were as wanted at the birth of their first grandchild as the exwife and daughter's mother. There's other exes within my exes family that have been extended the same courtesy and welcome.
My dad's family also extended courtesy to exes. My maternal gram always remained in contact with an exgf of my uncle's, but never to create discomfort, she really connected to my gram as extended in a familial sense and vice versa.
I agree that insistence in your case is unfair.
Granted it is your daughter's choice, at the same time such choices leave long lasting marks on relationships. There's give and take. A father deserves an invite over an aunt, unless the aunt raised her which isn't the case.