1) Cruelly 2) How bitter enemies speak 3) How diatribes are delivered 4) How pointed wit is presented 5) In a biting way 6) In a caustic way 7) In a sarcastic manner 8) In a sour fashion 9) In a tart manner 10) In a tart style 11) In an acerbic manner 12) Mordantly 13) Sarcastically 14) Tartly 15) With a tart tongue 
• (adv.) Sourly; tartly.
Ac'id·ly adverb Sourly; tartly. 
acidly Sourly.