Taylor Swift | John Mayer | Katy PerryUp until recently, Katy Perry and Taylor Swift had plenty of "bad blood" between them for years! The peak of their feud happened when Katy started dating John Mayer, after he ended his relationship with Taylor Swift. A bunch of shady tweets, tour accusations, and a few revenge songs later, Katy and John eventually broke up and the pop singers have since called a truce!
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