Question

Why is it even more cruel that Montresor threw his torch into the niche with Fortunato?

Answer 1

Montresor lures Fortunato by telling him he has obtained a pipe of Amontillado sherry. He mentions obtaining confirmation of the pipe's contents by inviting a fellow wine aficionado, Luchesi, for a private tasting. Not one to be made better of, Fortunato goes with Montresor to the wine cellars of the latter's house, where they wander in the catacombs. Montresor keeps giving Fortunato drinks to keep him drunk, finally arriving at a niche, where Montresor tells his friend that the Amontillado is within. Fortunato enters drunk and unsuspecting, allowing Montresor to chain him to the wall.

Montresor then proceeds to wall up the niche, entombing his friend alive. Fortunato sobers up faster than anticipated, though, and pleads with Montresor. Montresor ignores him and continues, eventually walling him in completely.

Notably though, in the story, Fortunato actually comes to the realization that this is actually what Montresor wants. Montresor doesn't want to murder Fortunato as much as he wants the psychological satisfaction of seeing and hearing him squirm as it dawns on him that he is going to die a slow death and he was so easily tricked into walking into this situation, and mocking him for it. In a final act of defiance, Fortunato refuses to play along at the end, and replaces his panic with cold silence. This silence catches Montresor off-balance, and its evident from narration that he was very confused and annoyed at being robbed of the chance to gloat properly, and even begins to feel "sick at heart" about what he is doing, because the sudden silence gives him no recourse but to actually consider the gravity of the act he is about to carry out. And even those fifty years later, there are still clear hints of Montresor being somewhat bitter about the fact Fortunato managed to outwit him at the end by taking all the fun out of his revenge.

Hope this helps :)