"Prior to getting sober, I was one of those people who was like, I don’t give a f**k, whatever," she said, "and I used that as an excuse to do whatever I wanted. I was a nightmare to work with."
The 23-year-old celebrated four years of sobriety earlier this year (16), but her efforts to change her lifestyle and behavior haven't come easy.
"I had to learn the hard way that I can’t do parties anymore," she continued. "Some people can go out and not be triggered, but that’s not the case for me."
Despite her four-year milestone, the singer knows there are still detractors out there who are waiting for her to mess up.
"I’m still underestimated… I still have more things to prove - not just about the things I can do with my voice," she said. "Some people think that because I’m young, I can’t stay sober. But these are things I want to prove to myself."
Demi prides herself on being honest about her past demons with her loved ones and loyal fans, adding: "I’d rather live my life free and open than closed off, where people like me for something that I’m not."