Demi Lovato Demi Lovato

Demi Lovato says she's clean and sober — and grateful for two famous friends.

"I'm not gonna lie. I was self-medicating," Lovato tells Seventeen magazine in the upcoming February issue. "I was doing things like drinking and using [drugs], like a lot of teens do to numb their pain."

Lovato completed a three-month treatment program last January, revealing that she was overcoming an eating disorder and bipolar disorder. The 19-year-old singer says she leaned on two people during those tough times: Miley Cyrus and Selena Gomez.

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"No matter how many times [Miley and I] fight, we will always be in each others' lives," she says. "Selena and I, we never fight. She's not a confrontational person at all. Both of them will never leave my life no matter what happens, because we've been through so much together."

Lovato, who released her third studio album in September, is happy with her progress today. "I don't drink, I don't do drugs, I don't throw up after my meals, I don't starve myself," she says. "There's nothing that I do that I feel ashamed of."