why is this clearly NOT a fold?
seems like (acording to you) everything points to you being beat, the tone of the voice, the lack of previous raises, it all rests on how likely she would display the same emotions with QQ/JJ/AK etc. If she wouldn't, it seems like it makes it a clear fold, not a clear call.
You should never throw KK away in this spot against an unknown , but I dont see the big deal with throwing KK away if the read is reliable enough, its only a hand that has X% equity vs an opponents range , if her range is AA only, then the equity is bad. Hand strength is pretty much relative to that of the opponent, not strong according to some back-page chart.
I dont know how much of a results orientation there is going on though, its easy to think "hmm, she might have AA here" at the time, and then after the event think "man I was 100% sure she had AA and called anyways" just because she happened to have it this time.
I dont think I'd ever be able to read/know someone well enough to throw away KK in this spot given the meagre action (ive done it in cash games enough times, but the action there is more then bet/push) so I'd never fold, but if you are being honest and the read/knowledge of opponent IS strong enough, then folding here is clearly the best play.