Inside the Taylor Swift & Katy Perry feud

Taylor Swift is furious at someone - and it's not an ex. When asked in Rolling Stone about the mystery subject of her song "Bad Blood," Swift, 24, declared, "We're just straight-up enemies," and added that the rival tried to "sabotage" her tour. The nemesis, multiple sources tell Us, is Katy Perry, 29. In fact, the day after Swift's interview went live, "Dark Horse" singer Perry tweeted an apparent reply to the jab. Referencing Mean Girls, she posted September 9, "Watch out for Regina George in sheep's clothing." Says a Perry pal, "She knows the song is about her."
Hear her roar The professional spat is ostensibly about some backup dancers Perry poached from Swift midtour. "She tried to steal them," says a Swift source. Counters the Perry pal, "They had already worked with Katy and were loyal to her." But a second Swift source points to a more personal rift. Not only did Perry violate girl code by dating Swift's ex John Mayer, Swift thought Perry "wasn't nice" to her: "She would insult her in private, then publicly say 'I love you.'" Finally, enough was enough. Says the pal, "Taylor is sticking up for herself."