I always think horror books can only be 'scary' as such when you find the exact right one for you. The things that scare us are so personal. I actually found Pet Sematary a tough read for me, as I am a parent myself and my children were the same age as the ones in the story when I read it. In terms of stories that frightened me (to the degree it's possible in book form), I remember a very unnerving ghost story type book called 'Knock Knock' by S.P Miskowski. It made me so uncomfortable I actually gave it away in the end (which I rarely ever do). There is also a short story by an author named Ania Ahlborn (who is wonderfully talented) called 'The Governess' which I thought was a fantastic ghost story. Although again, being a parent (especially in the age of baby monitors) will make this story more effective. Another author who writes wonderfully creepy, graphic and psychological stories, is Kealan Patrick Burke. I think 'Blanky' was one of his best, and he has many books of short stories worth a read.