Add insult to injury
This means, of course, to make matters worse or to humiliate someone who has already been hurt. It is in fact a very ancient saying probably much older than the first citation of the concept in Latin from the work of the Roman writer Phaedrus c. 8 AD. Phaedrus tells the story of a bald headed man slapping hard at a fly on his head, missing the fly and hurting his head in the process. The fly jeers at him, “What will you do to yourself now that you have added insult to injury?” The saying makes its first appearance in English during the mid-18th century.