The Raven King question

Hello! I wanted to ask for some help from this community because for the past few years I have been searching for a specific book I read quite a while ago but I never wrote the name or author down. It was one of the best and most touching books I have ever read and any help will be deeply appreciated.
plot/story-line: A girl feels guilty for killing her baby sister (her baby sister chocked on a small button that the girl had sewn onto the girls clothing) and ever since her baby sister died she has been going to therapy sessions in her school with a bunch of other friends, one day someone new joins the group and this boy has quite a rough past too (he was driving whilst drunk one night and crashed, the crash ended up killing all his friends). At first the girl wishes nothing to do with him however inevitably they become closer and they help each other with their traumas. The girl keeps a scrapbook of different ways people have died and is wary of all these ways because she wants to be as safe as humanly possible however the boy slowly teaches her to face her fears and the world is not as dangerous as it seems just unfair at times. He doesn't just help her heal and overcome her fears, he also mends her family. Later on, the pair make a mini video for a competition because the prize is a lot of free pet food but the boy is resistant in letting the girl post his mini-movie (because he's afraid someone will recognise his name and then expose his past to the girl). Inevitably the boy's past is revealed and their friendship is put through immense pressure and trouble.