JB did NOT initially blame Sheila because he had no idea of the extent of her mental issues. What he understood later was that which had been " fed " to him by those whose limited knowledge,blamed schizophrenia,instead of its cause. One doesn't suddenly develop schizophrenia.
I would hazard a guess that JB got the shock of his life after reading about the traumatic and tumultuous life that Sheila had endured that brought about her mental illness. Sheila was on a downward spiral. Anyone with half an eye could have seen that. Her friends,particularly when they'd remarked on how different she'd looked,scary and staring,since her final hospital visit.
JB has never seen himself as the victim,it's others who've added that " he too is a victim ". He certainly hasn't come across as a " feel sorry for me " person,of which there are many,but I wouldn't class them ALL as being psychopaths. I can't be doing with these sort of people either ( sympathy seekers )