Though the 22-year-old star has been very private about him in the past, Lovato openend up about her relationship with the actor for the first time, reported People magazine.
"People say that relapses happen before you use. Your mind starts setting up the relapse before you take that drink or that first hit," she said.
"The times we'd broken up, I had already gone to that place of, 'Yeah, this is what's happening.' I didn't realize it at the time, but I just wanted to sabotage everything around me so that I could sabotage myself."
"People told him, 'You should probably leave. She's on a spiral, and you're going to be sucked down with it,'" she said of Valderrama, 35.
"But he was like, 'I'm not leaving. This is somebody I really care about,'" she added.