'Off The Rails!' Inside Demi Lovato’s Tragic Addiction Relapse

After being a spokesperson for sobriety for six years, Demi Lovato admitted she relapsed today in a heartbreaking new song.

And now, RadarOnline.com can exclusively reveal details behind the singer's horrific downward spiral.

“Demi relapsed about two months ago because she stopped the accountability portion of her recovery,” one source explained to RadarOnline.com.

Another confidant added: “Everyone knows Demi is off the rails.”

Insiders claimed Lovato, 25, has slipped back into the same out-of-control behavior that first drove her to rehab years ago — and she's not accepting help.

“No one can get her attention,” said a friend. “Her team tried to hire a sober coach, and she went nuts!”

Lovato confessed her tragic slip in the words of her new song, “Sober.”

In the heartbreaking lyrics, Lovato confesses she’s “dying inside” and she just wants to “cave in” and not fight.

The song ends with the line: “I’m so sorry, I’m not sober anymore.”

Adding to loved ones’ serious concerns, Lovato has been acting bizarrely, according to insiders, and she is no longer pictured on the website of CAST Centers, the West Hollywood rehab facility where she received treatment.

During her recent concert tour, Lovato provided time before each of her shows to promote CAST and have a guest speaker outline their addiction hardships and how they overcame them.

Mike Bayer, the center’s founder, said he also looked at the talks as a way to help Lovato.

“I was trying to create an experience for her in every city where she would be able to get self-help,” he explained.

Bayer did not return RadarOnline.com’s calls asking why Lovato has vanished from the center’s site.

In April, Lovato was spotted partying at the drug-fueled music festival Coachella, and left a Hollywood strip club looking worse for the wear with Bella Thorne later that month.

Just as troubling, Lovato's had to cancel multiple tour dates, and now, sources said, the “Sorry Not Sorry” singer's become a no-show at recovery meetings.

As RadarOnline.com reported, Lovato has been battling her demons since her teens, when she admitted to suffering from depression, feuding with family — and injuring herself with deep cuts to the wrist.

The performer, who appeared on Barney and Friends as a child, confessed to sneaking vodka in Sprite bottles and claimed she fed her cocaine addiction with hourly doses of the deadly drug.