Demi Lovato shares live performance of 'Sober,' says she is 'a new person'

Demi Lovato has always been forthright with her fans about her struggles with addiction.

Now in a new track, "Sober," that the pop star released last week, she sings, "Mama, I'm so sorry I'm not sober anymore/And daddy please forgive me for the drinks spilled on the floor."

Lovato, 25, tweeted a link to the song, writing, "My truth."

Lovate also on Sunday shared a video clip of her performing "Sober" during a concert in Lisbon, Portugal. In the video, Lovato appeared to be fighting back tears as she sang, "I'm sorry for the fans I lost who watched me fall again/I want to be a role model but I'm only human."

"Tonight I took the stage, a new person with a new life," she wrote on Twitter. "Thank you to everyone who has supported me throughout this journey. It will never be forgotten."

The singer has been outspoken about her battles with bipolar disorder and substance abuse. A former patient turned advocate, she is now co-owner of Comprehensive Assistance Support Treatment [CAST] Centers, a wellness and recovery program that personally helped her during her battle with substance abuse.

In March, Lovato celebrated six years sober.

But in May, she hinted that there was more to tell, writing, "I'll share my truth soon."

A rep for the singer did not immediately return a request from ABC News for comment.