The 'One That Got Away' singer, who split with ex-husband Brand in December, is currently working on the follow-up to the record-breaking Teenage Dream.
A source told Grazia magazine: "Katy goes from being angry one minute to upset the next.
"She really is laying everything out there in her music, which she says has been extremely therapeutic. This new album will certainly be explosive."
Claiming that Rihanna "fully encouraged" Perry's passionate rendition of new single 'Part of Me' at the Grammy Awards, the insider further alleged: "Katy's performance was intended to stick two fingers up at Russell."
She sang: "You can keep the diamond ring. It don't mean nothing anyway.
"You chewed me up and spit me out / Like I was poison in your mouth. You ripped me off, your love was cheap / Was always tearing at the seams."
Meanwhile, the supposed aide added: "When they signed the divorce papers, it was upsetting but fairly amicable.
"Now it seems Katy has gone into the next stage of grieving and, with all these rumors about new women, she's mad as hell.
"Katy is furious with Russell for not trying to save their marriage. He broke her heart and it's only natural if she wants him to suffer pain like she has."
> Russell Brand 'dating Mexican painter' following Katy Perry split
Watch Katy Perry performing 'Part of Me' at last week's Grammy Awards below: