Martyrs was awful and I didn't even watch the entire last third or so of the film lmao. I was like 13 but I'd read reviews and knew the end was meant to be awful so I casually stopped watching
I'm not a fan of gore at all though so I avoid films like that. In terms of just like, horribleness, I watched World of Kanako recently and it was really hard to get through. It was just relentlessly negative and nihilistic.