Lovato, who has battled substance abuse and eating disorder issues in the past, has nothing but kind words for Gomez.
"Selena is, I've known her for 14 years and we've been best friends," the former X Factor judge told E! News. "That's all of her business, and I just want to let her do her thing. And yeah, she's amazing. I love her."
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"It's just important to me, for people to see that it's not, when you're a drug addict, that it's your fault," Lovato said. "It's not even a conscious decision. When you're in your disease, you do things impulsively. You don't think forward. When you're a drug addict, you are in pain and this is the only way you know how to medicate it."
Lovato is also very vocal about addiction on social media and even wrote an open letter on Twitter last week after Hoffman's death.
"That open letter was basically me saying have compassion for the people that die of this disease," she continued. "People need to look at this as a disease that it is. It's a mental illness...addiction is a mental illness. There are ways to get treatment for it, which is medicine—medicine as in therapy and whatever it is they need help with. But don't blame Philip Seymour Hoffman for taking so much, or whatever it was. It's a really hard thing to control and I definitely don't think it was his fault."
For more of Lovato's exclusive interview, tune in to E! News tonight at 7 and 11:30 p.m.