I feel like I need to call bullshit on so many things about this book. The narrator isn't helping. I think he's getting some inflections way off and it's making parts of the dialogue seem wrong - flippant when it should be serious, stuff like that.
The MC seems to think that everyone will believe him and do what he wants because he says "I swear I'm not lying" or "I swear I'm not a killer" or "I swear I won't say anything" and then he gets his way. BS, I say.