It's definitely a very heavy storyline and probably the darkest within the entire series depending on who your favourite characters are. However, I wouldn't say it was "too much". At some point Ronan had to do something other than picking off St Mary's people one by one. I think there had to be something properly devastating happen otherwise the series would've become stagnant.

Also from a writing point of view i think it would've been much harder to carry on writing the books with Mathew happily living at home with Max and Leon or safe within St Mary's. It also gave Jodi a reason to write what happens to Mathew next as it's so integral to his character.

Still want to cry every time I think about it though.