Sheryl Crow sat down with Vanity Fair Magazine for an in depth interview – discussing her battle against breast cancer and her break-up with Lance Armstrong.

Crow says it was difficult to be apart from ex-fiancé Lance Armstrong after she was diagnosed with breast cancer earlier this year. "It was difficult, you know, I know he wanted to be there.” Crow and Armstrong announced their breakup in February. The 44-year-old rocker says the split was "devastating" for both of them. "I do think about Lance every day," she says. "And I think about his kids every day." When Crow learned she had cancer, she contacted the seven-time Tour de France champion, who was on a solo road trip from Lake Tahoe to Oregon.

"When I got that news, I can't even describe it," says Armstrong, who is a survivor of testicular cancer. "It was the cruelest twist. ... I actually turned around to make the drive to L.A. We talked along the way and she said, `You know, I just don't think that's a great idea.' According to Armstrong, Crow told him she felt "it would be hard on her in trying to manage the breakup and the diagnosis. And I totally understood."

Says the 34-year-old Armstrong of their split: "We were at different points in our lives." Crow says her romantic relationships never seem to lead to the altar. "I think that if I wanted to be married I would be married by now," she says. "And, for whatever reason, I haven't done it. I've picked people who've helped me to not make that happen."Crow will begin a tour with John Mayer on Aug. 24 in Pittsburgh. A portion of the proceeds will be donated to The Breast Cancer Research Foundation.