Responses
As I said some comments up, and maybe I'll be proven wrong in the next chapters, I don't think he's invalidating what he did to Inseob, he's just saying that he'll continue being an awfully horrible person because he can only think about what he wants to do and not about what should be right or wrong. He made the right exemple of "if I wanna make a fire in the house, knowing that you're there sleeping, I'll do it anyway just because I want to". To us that's just horrible, but to him I think he'll feel it like a setback
I don't want to invalidate a disorder but his disorder does NOT excuse everything he did to him. Sorry but if you rape someone you cant blame it on the fact that u lack empathy