Well, it's too late anyway.
I can't see how she will work with him on her next album though. She's a smart girl. She won't say anything and won't take sides but she knows she will receives a serious backlash if she'd work with him.
Of course, she doesn't have to say something but for an artist like her, who usually, is not afraid to speak her mind, her silence is quite telling. Which is odd because Katy knew Kesha before she became famous.