SOLVED. YA Horror/Thriller novel. Killer obsesses over girl after he killed her parents. [s]

[Victoria]

It's a fiction young adult novel. I think I read it about 4 years ago. It is about a girl who's parents were killed when she was younger but she was left alive. The killer obsesses over her for years. She lives with her relatives afterwards. As she gets older she learns how to defend herself. One day she gets a email about a contest to meet her favorite author. She enters hoping that she'll win. She wins and convinces her relatives to let her stay the week there. She gets picked up to be driven there. She arrives at a house in the middle of nowhere with several other people who also won. They are told they will meet the author at the end of the week. She ends up falling in love with this boy that is there. At the end of the week they go to this weird amusement park where they are killed. It turns out this was all set up by the killer who has been obsessing over her for years all to get to her. She ends up escaping with the boys help but has to leave the boy she gives him her necklace as a promise that she will come back for him. She gets away and I think when she does come back with the police everything is gone. There is a sequel to the book that is about the killer luring her to him by saying he has the boy and the boy is still alive and of she doesn't come he will kill the boy. I really liked these books and would love to read them again but I can't remember what they were called. Please help

[Rainbowheart]

The Girl I Used to Be?

[Jessica (Goldenfurpro)]

Welcome to the Dark House?

[Victoria]

It's welcome to the dark house thank you so much