What's A Horror Movie So Disturbing, You Actually Had To Just Stop Watching It?

So, with that in mind, I want to know: What's a horror movie so disturbing, you couldn't make it to the end? Like, I'm not talking about "so-badly-made-I-had-to-stop-watching" movies or "so-boring-I-turned-it-off-and-fell-asleep" movies — I mean "so-messed-up-I-had-to-turn-it-off-before-I-needed-therapy" movies.