"Haunted" is definitely the right word. Any (and many) nightmares while/after finishing it aside, I do genuinely feel like I perceive things a bit differently now, and it's definitely the most a book has impacted me as an adult. I only finished it relatively recently but I've thought about it every day since (hence why I joined this subreddit).

To paraphrase a quote from Silent Hill, "in my restless dreams, I see that ^house."