It's crazy how a simple misfortune of someone who dreamt of nothing but great thing for his family is seen as the cause of a their problems the moment he is strike with such misfortune that leads to him being unable to support them. Whatever "it" was that Gregory turned to, that big of a spite he did not deserve!.
It is morbid and I felt more disturbed and repulsed the further I read, the end being most nauseating, yet the matter-of-fact tone of the casual narrator never changes throughout, being darkly in contrast to the strangeness of things he is describing, whereas he speaks as if he has just noticed the weather change.
Also, it seems to be very metaphorical. Do read.