A Tale Of Two Sisters is the epitome of a psychological horror, and it's really fun to analyze. It has an American remake (The Uninvited) if you don't wanna do a foreign film, but that's not half as amazing or detailed.
Confessions is my fav movie of all time but I wouldn't pick it since I've never understood why it gets labeled as a horror
I mean, it's obviously disturbing but so are a lot of other dramas. It has no horror movie elements to me.