Montresor regrets in his actions

Although Montresor extracts the justice he feels is owed him from his unfortunate friend, Fortunato, it's important to keep in mind that this was his good friend. The lack of response from Fortunato in the final moments of his ordeal, strike a certain anxiety in Montresor, one would not expect to find in a person who has just successfully completed a well laid plan. The fact that this story is being told in retrospect fifty years later, indicates he still thinks about it constantly, making the revenge a Pyrrhic victory at best.