Speaking to The Hollywood Reporter ahead of the release of her new 3D concert movie Part Of Me, the 27-year old reveals the difficulty she faced as a result of her 14-month marriage to Brand coming to an end.
K-Pez tells the publication: "There were times when 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 eyes 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.’”
She went on to state that it's impossible for anyone else to know what went on inside her brief union to the British comedian, claiming: "Nobody knows what really happened except the two people who are in it."
Part of her vision for the movie was to document her relationship with Russell as it crumbled just as her career was launching into the stratosphere with a record-breaking string of hit singles from Teenage Dream.
That kind of honesty was in keeping with her heart-on-sleeve method of writing songs, with Perry explaining: "Honesty has always worked for me ... so if it ain't broke, why f***ing fix it?"
After putting up $2 million of her own money to make Part Of Me a reality, Perry and her team are expecting the movie to have an opening to rival Justin Bieber's Never Say Never, which earned over $30 million first weekend.
First, though, she had to convince her nervous business manager that it was worth dropping the cash to film her November 2011 concert at Los Angeles' Staples Centre in 3D.
"I was like, 'Please trust me,'" Katy says she told him. "That's kind of been the mantra I've said to everyone my whole life: 'Trust me, I have a vision.'"
In the same interview, the Wide Awake singer also revealed plans to start her own record label, stating: "When it does come to fruition, I'm going to try and avoid the things that take away any fighting chance for an artist to have financial success,"
"As people are coming to me with opportunities, I'm thinking, 'How would I want to be treated?'"