It's so obvious he's mentaly broken! And before entering any discussion about the right and and the wrong, a MC does not have to be good guy nor a bad guy! He just is! And we're reading a made up story, plus we do not need to agree with his action! But sadly people judge a story by it's content and not how the story is told! It's like saying a movie about, let's say Hitler life(or any psychopath), is bad because he's doing bad stuff!
This is my first time reading, and probably the story isn't anything special