Perry hid divorce pain for fans

Katy Perry has revealed she broke down in tears moments before going on stage as she struggled with her marriage problems.

The Firework singer opened up to The Hollywood Reporter about her break-up from ex-husband Russell Brand as she defended her decision to document their relationship in her 3D concert movie Katy Perry: Part Of Me.

Katy said of one scene which shows her breakdown backstage: "What was going on in my personal life was so overwhelming that I had to bend over to let those tears fall straight out of my eye sockets and not my false lashes just as I'm about to go up on that ramp and sing Teenage Dream.

"I had to smack myself across the face and say, 'These problems are my problems, they are not my audience's problems, learn to separate that'."

Katy and Russell's relationship was constantly under the spotlight after they met at the MTV Video Music Awards in September 2009, married in October in 2010 and split just 14 months later.

The 27-year-old singer admitted the film includes footage that two years ago she "wouldn't feel completely comfortable with people seeing - me crying or looking like a hot mess".

Russell reportedly wanted footage of their relationship taken out of the film.

But Katy said the film was from the heart "like how I write songs".

She added: "Honesty has always worked for me. So if it ain't broke, why f***ing fix it?"