"Of life, of crown, of queen, at once despatch'd."
So the originals read, except 4to 1603, which has depriv'd, perhaps a better reading. 'Despatch'd,' which seems to be more forceable, is to be taken in the sense of dépêché, Fr., hurried away, and 'of' in its original sense of from.
"Cut off even in the blossoms of my sin."
Better to read 'blossom' and 'sins.'
"O horrible! O horrible! most horrible."
Beyond question, as Johnson saw, this exclamation belongs to Hamlet. Ham. and Ghost had been effaced.