The Fear By Natasha Preston

Don't be afraid. Be terrified. 
It’s just a stupid meme that’s going around their small fishing town in the dead of winter—people reposting and sharing their biggest fear. But when her classmates start turning up dead—dying in the way that they said scared them the most—Izzy knows it’s no joke.
With each death hitting closer to home, Izzy sets out to try to stop the killer. Could her older sister’s friend Tristan have something to do with the deaths? He’s given her some strange vibes. Or what about his brooding cousin, Axel? But he’s in her classes at school. He’s not a murderer . . . is he? Izzie’s soon on a path that will lead her right to the killer . . . and her own worst nightmare.