Katy Perry Says She'll Collaborate With Taylor Swift 'If She Says Sorry'

She's waiting for an apology. Katy Perry revealed during a Twitter Q&A on Saturday, September 10, that she'd collaborate with nemesis Taylor Swift on one condition: The "Bad Blood" singer has to say sorry.While waiting in a This article originally appeared on www.usmagazine.com: Katy Perry Says She'll Collaborate With Taylor Swift 'If She Says Sorry'