Answer:
The story in question is The Black Cat by Edgar Allan Poe.
1. The narrator states that he is not mad because the events he is about to narrate are very much out of the ordinary. Mad here refers to the state of not being in full control of ones perceptions, insane or mentally ill.
2. The narrators statement tells us that he really wants people to believe what he is about to say and is worried people may dissmiss his story as unreal.
3. He reveals that he is going to kick the bucket on the morrow.
4. He means that other people upon consideration of his story will not take appreciation of the nuances and the feelings of dread that it evokes within him. But that some person may process the entire ordeal in purely logic.
Cheers!
The main idea is that you should nice to your friends
Revealing the outcome in the prologue dilutes the story of any suspense. It is mandatory for any reader to read the prologue to know the basics of the story. And being told what is going to happen is like knowing that Darth Vader is Luke's father before you even watch the movies. I would prefer not to be told what happens in the story, because it gives the novel or section of writing the upper hand in obtaining and keeping the readers attention throughout the story.
I hope this helps you!