Billboard

Katy Perry is talking love and loss in a new interview for Billboard magazine.

In the latest issue, the 28-year-old "Roar" singer gushes about boyfriend John Mayer.

"He literally is a genius, as is evident from his songwriting. I always tell him, 'Darling, you know I'm going to have to give your mind to science after you've passed, because we're going to have to understand how all these sparks work,'" Perry told Billboard.

Perry said Mayer was brilliant when it came to other things as well.

"We'll be in bed, and he'll be doing the crossword puzzle. Every night, he tries to finish it in under 10 minutes. When he puts his mind to something, he really gets it done very well. I always ask for his help," she said.

Perry may be high on love right now, but she admits that she was devastated at the end of 2011 during the breakup of her 14-month marriage to comedian Russell Brand.

"By the Grace of God," a song on her latest album, "Prism," reflects the dark thoughts she entertained then.

"That song is evident of how tough it really was at a certain point," Perry told Billboard. "I asked myself, 'Do I want to endure? Should I continue living?' All the songs are real-life moments. I can only write autobiographically. I put all the evidence in the music. I tell my fans if they want to know the real truth about stuff, just listen to the songs."

In the midst of her marriage crumbling, Perry said she was "shaded" by ABC News' Barbara Walters after showing up late to tape her interview for Walters "Most Fascinating People of 2011? special.

"I shouldn't have done the interview: I was playing Madison Square Garden that same night, and I knew that the end of my marriage was coming. I was just exhausted and stressed," Perry told Billboard. "I'd prepped everyone that I was running late, but Barbara showed up at the original time anyway. When I got there, I apologized immediately, but then she said to me, 'You know, I've only ever waited for one other person this long, and you know who that person was? Judy Garland. You know how she turned out, right?'"

"I was like, 'Oh, snap!" Perry said. "I think it's the coolest thing that Barbara Walters shaded me. I just couldn't tell her as we were sitting down for a mega-interview, 'Hey, my marriage is falling apart. Give me a break.'"