at the cackling verge

You know those scenes in movies where the mad scientist or other generally insane character lets loose with that crazy cackling as they go over the edge into whatever act of insanity they are committing?

I no longer think that kind of behavior is fictional.

Because I can feel it knocking at the door, and only by an active effort of self-restraint am I keeping it at bay.

at the precipice of crazy

at the precipice of crazy…