“You might have got the impression that there is a little bit more to Aunt Petunia than meets the eye, and you will find out what it is. She is not a squib, although that is a very good guess. Oh, I am giving a lot away here. I am being shockingly indiscreet." - J.K. Rowling.
If the reveal had been that Petunia was a witch ~ Several years after the war, Harry tracks his aunt down to confront her with what he witnessed in the pensieve.
if you’re ever really sad you should probably go look at cake wrecks. your life won’t improve or anything but you’ll probably be too busy trying to decide why the word “ultrasound” is suddenly so funny to you to remember why you were sad, at least for a little while