Demi Lovato is opening up about her battle with alcohol and drugs, her eating disorder, self-mutilation and her volatile friendship with fellow Disney alum Miley Cyrus.

"[Miley] and I are strong headed. When we fight it's brutal and we're like, 'We're never going to be friends again!' Then two days later, were like, 'I love you and I miss you!'" The nineteen-year-old tells the new issue of Seventeen magazine.

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One of the two friends' "brutal" fights went public in 2008 after Miley posted a YouTube video mocking Lovato and Selena Gomez.

Then, in 2009 they got into a Twitter feud following a snippy remark Lovato made after Miley posted a photo of the two of them together, with the comment: "Now this is what true friendship looks like. None of that hollywood c***. @ddlovato I miss you :)"

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Disney star Demi Lovato talked candidly about her battle with an eating disorder which ultimately led her to nearly three months in a rehab treatment facility, and RadarOnline.com has learned she admits it’s a “life-long disease.”

“There have been times when I definitely have been tempted to get rid of my dinner,” the 18-year-old Camp Rock actress told Seventeen Magazine in a recent interview.

“But I will deal with it for the rest of my life because it’s a life-long disease. I don’t think there’s going to be a day when I don’t think about food or my body, but I’m living with it, and I wish I could tell young girls to find their safe place and stay with it.”