You're right, the answer is caring. :)
Well, just the fact that the characters are all dressed up for a masquerade party, already adds to the eerie mood. But what really seals the coffin is when Montressor lures Fortunato into the catacombs, and then ties him up. You really get the whole creepo-vibe, when Montressor starts to seal up the "tomb". Hope this helps you a lot.
Answer:
I think the answer would be, "O coward that I am, to live so long, / To see my best friend ta'en before my face!".
Explanation:
I'm not exactly sure if this is correct, but I think it states that he's been guilty for a long time and he can't escape...?
