for me
Nil by Mouth ( only seen it once when it was new, and can’t remember much about it beyond it just being relentlessly bleak. Never felt an urge to see it again)
Breaking the Waves (when she sails off on a little boat to that big boat, so grim)
Videdrome (something about the bit when James Woods puts a videotape in his tummy)
Man Bites Dog (I know it’s supposed to be some kind of satire, but I just found it grim. Probably not helped by the fact I watched it when I had appendicitis)
I’ve not seen a lot of the obvious “disturbing” films (irreversible, Serbian film. Doubt I ever will, not really for me)