The documentary, called Part of Me, chronicles a year of the performer's life during her world tour in 2011.
Perry was adamant about including her divorce from Brand on camera, including the moment she found out the comedian had filed divorce papers just minutes before having to go on stage in Brazil.
She told the Daily Mail: "Watching it in the edit suite later I was saying, 'This is okay...'. I just needed a shoulder to help me walk up the steps. I had to bend over so my false eyelashes didn't come off. I couldn't let the tears stream."
Since her split from Brand in October 2010, the 'Wide Awake' singer has been linked to Florence + the Machine guitarist Robert Ackroyd.
Despite her unhappy break-up from Brand, the singer added: "I still like boys from London, all except one."
Katy Perry: Part of Me is scheduled for release on July 5 in the US and UK.
Watch a clip from Katy Perry: Part of Me below: