I think Japanese use ~くれる and stuff also when someone does something for someone else even if that someone else doesn’t appreciate it. It emphasises that the deed has an impact on someone else. But that’s just my understanding.
i.e.:
とんでもないことをしてくれました = he did something outrageous that effected me.
とんでもないことをしました = he did something outrageous (and I was just witnessing it).
What a chapter.
I really enjoyed reading the mother’s thoughts in a dark humor sense.
So far, it seems like this story is set up so that you think you know what happened at the beginning, but as you read on you find out more about the truth.
I’m under the impression that the reader is supposed to have a reversal of how they feel about A and B. In the first chapter, A was made to seem like the more atrocious of the two. Most comments here had a stronger reaction to him. But if it’s true that B through her into the pool after she opened her eyes, and not because he was afraid, well… Maybe that’s a part of the societal commentary of the story.
Reading this chapter I’m also more convinced that when A was talking about trying to ramp up the stakes of his stories to get a reaction, he was making up the more serious claims (in order to do a reversal of how the reader feels like with B, not that A or B were ever in the clear).
I am very curious what information will be revealed next.
I read that as sarcasm at the time, I believe. Like you could say “thanks to you doing x, this terrible thing happened” in English as well. (Unless you can’t 
)
I was talking to a Japanese person who had read the book yesterday (and another one who hadn’t, but I showed them the passage*) and they both also said it was sarcasm.
Case closed! 
*they looked horrified when I told them the plot of the book 
