In this week’s PEOPLE cover story, Mariah Carey reveals for the first time her battle with bipolar disorder.

Although she was first diagnosed in 2001 (when she was hospitalized for a physical and mental breakdown), “I didn’t want to believe it,” the superstar singer-songwriter tells PEOPLE editor in chief Jess Cagle.

Carey says she finally sought treatment recently after “the hardest couple of years I’ve been through” — years of professional upheaval, an E! reality show and romantic drama.

“Until recently I lived in denial and isolation and in constant fear someone would expose me,” she says. “It was too heavy a burden to carry and I simply couldn’t do that anymore. I sought and received treatment, I put positive people around me and I got back to doing what I love — writing songs and making music.”

Courtesy of People Magazine