the anguish of recognition
The phrase is suggestive of something beyond the mere identification of the body. Victor surely recognizes his responsibility for this death. Perhaps the extremity of his phrase is also intended to accentuate the point at which he finds himself looking, as it were, into a mirror, confronting a second self who has been murdered by a being who is likewise an extension of himself. The shock, as his reaction strongly testifies, is psychologically as well as physically convulsive.