He's a born sociopath. Can't relate to people and feelings at all, doesn't even bat an eye when his wife dies.
The only thing he enjoys is other peoples suffering (including his sickly wife's), but he doesn't want it to be like this. But he can't find anything to help change him.
Eventually he snaps and embraces that his purpose in life must be to kill everybody or cause as must suffering as he can, since it's the only thing that makes him feel alive.