Katy Perry is reportedly finding working on her album "therapeutic" following the breakdown of her marriage.

The singer and her husband Russell Brand announced their split in December last year. Katy is believed to have been left devastated after the British comic actor filed for divorce and has been channelling her heartbreak into new material.

"Katy goes from being angry one minute to upset the next. And she really is laying everything out there in her music, which she says has been extremely therapeutic," a source told British magazine Grazia. "This new album will certainly be explosive."

Katy sent shockwaves around the showbiz world earlier this month with her feisty appearance at the Grammys.

She performed her new single Part of Me, which appeared to feature lyrics about her impending divorce. As flames raged around the stage, Katy sang the lines You can keep the diamond ring. It don't mean nothing anyway.'

"Katy's performance was intended to stick two fingers up at Russell. Her best friend Rihanna fully encouraged it, too," the source added.

Although Katy and Russell vowed to remain on good terms, it appears their relationship has turned sour since they signed divorce papers on February 8.

The 27-year-old singer is recently believed to have visited Russell to discuss the final divorce arrangements and return her wedding ring. However, she is rumoured to have "sobbed her heart out" as she left.

Katy has also been shocked by rumours that Russell, 36, is now dating a woman he met at a yoga class.

"It's fair to say that in the space of just two weeks, things have become very nasty," the source revealed. "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 rumours 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."