The secret of monologues is to create the scene and the dramatic situation in the first few lines of monologue: "You what? You..." The next line must state the total dramatic situation, but you must write it.
Then make very clear to the audience what the relationship is between the speaker and the imaginary listener. The last step is projecting the solution to the dramatic conflict. Here is a sample, only a sample:
"You what? You wrapped my Porsche around the City Hall flagpole?
When I hired you as my chauffeur, you didn't mention you couldn't drive!
Luckily, I'm the mayor!"