Mariah Carey opens up for the first time about battling bipolar II disorder. The iconic singer tells PEOPLE that it’s been a difficult journey thus far, but she’s ready to speak about her experience.

“I didn’t want to believe it,” she said. “Until recently I lived in denial and isolation and in constant fear someone would expose me. 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.”

“Bipolar I disorder involves periods of severe mood episodes from mania to depression,” according to WebMD. “Bipolar II disorder is a milder form of mood elevation, involving milder episodes of hypomania that alternate with periods of severe depression.”

Also known as manic depression, the bipolar disorder has impacted Carey’s life in several ways, she says. “For a long time I thought I had a severe sleep disorder,” she explained. “But it wasn’t normal insomnia and I wasn’t lying awake counting sheep. I was working and working and working … I was irritable and in constant fear of letting people down. It turns out that I was experiencing a form of mania. Eventually, I would just hit a wall. I guess my depressive episodes were characterized by having very low energy. I would feel so lonely and sad — even guilty that I wasn’t doing what I needed to be doing for my career.”

Things are also looking better for Carey, who is planning to release a new album later this year. Moving beyond “the hardest couple of years,” Mariah is now in therapy. She’s also taking medication for bipolar II disorder. “I’m actually taking medication that seems to be pretty good”, she also added. “It’s not making me feel too tired or sluggish or anything like that. Finding the proper balance is what is most important.”

Moreover, she hopes that coming out with her story will help others. “I’m hopeful we can get to a place where the stigma is lifted from people going through anything alone,” she said. “It can be incredibly isolating. It does not have to define you and I refuse to allow it to define me or control me.”