The first way the author teaches us that revenge is guilt is through this quote "For a brief moment I hesitated- I trembled." This shows us that even though he wanted revenge hes had a thought of sympathy and second guessing on his decision. He showed mercy for awhile. A thought of instant brought him back to his way.
The second way the author teaches us that revenge is guilt is by him calling for Fortunato and receiving no answer. this lead him to tear