to say or do sth unkind deliberately; to make sb who is unhappy feel even more unhappy
TURN / TWIST THE KNIFE (IN THE WOUND)
Meaning of TURN / TWIST THE KNIFE (IN THE WOUND) in English
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005