My daughters caught me when they were 11&13. I didn't want to tell them but felt obligated to explain their father fully dressed in women's clothes. My daughters explained that cross dressing was covered in sex ed. I never did tell my son.
Just my opinion but I think that 4 years old is too young to handle such a MOAS.
As for your wife's opinion. Never ever forget rule 1. If the wife ain't happy no one is happy.
