Justin Bieber In Diddy Tailspin: 'Baby' Singer 'Gripped with Fear' Over Revelations About His Years As 'Sex Predator' Rapper's Teen 'Buddy'

Fragile pop star Justin Bieber is on the verge of a total collapse as he faces the shattering possibility that sordid details about his relationship with indicted sex fiend Sean "Diddy" Combs will soon be exposed for all the world to see, sources said.

Insiders close to the 30-year-old “Stay” singer said he's "shut himself off from the world" as he wrestles with his disturbing past when he was a fresh-faced 15-year-old trying to impress a music industry mogul whose alleged degenerate ways have now come to light.

A member of Bieber's inner circle told RadarOnline.com: "No one knows what's going on with Justin. It's like he's fallen off the map since Diddy's arrest and all the sick details coming out. People are genuinely worried about him."

Justin — who recently became a dad for the first time with model wife Hailey Baldwin — partied hard during Diddy's now-infamous "Freak Off" orgies.

Said the insider: "Dealing with that and being a new dad probably has hiim stressed as hell."

Justin was just 13 in 2008 when he was signed to manager Scooter Braun and Usher's music label.

Through Usher, he met Diddy, now 54, and became the rap impresario's protege.

As a recently unearthed video reveals, the two buddies spent a wild weekend together in 2009.

In the video, the rapper alarmingly crowed: "Where we're hanging out and what we're doing, we can't really disclose but it's definitely a 15-year-old's dream.

"I have been given custody of him. I don't have legal guardianship of him, but for the next 48 hours, he's with me, and we're gonna go full crazy."

It's long been rumored Diddy plied Justin with drugs and booze and brought him to clubs when he was underage.

Justin himself confessed he struggled with drug use as a young adult, and while he dealt with pain that nearly drove him to the unthinkable.

"I think there were times when I was really, really suicidal, like man is this pain never going away," he once shared.

Bieber, who has seen his star cool considerably in recent years, is terrified details of those troubled times will be laid bare as Diddy faces sex-trafficking and assault charges in what promises to be a sensational criminal trial, sources said.

Recent images of a gaunt Bieber have also raised new fears about his state of mind.

Said the source: "I can only imagine the horrors he carries around with him — and now he has to deal with all this stuff being dredged up, threatening his marriage AND career. No one would be surprised if he has a complete breakdown!"

Have a tip? Send it to us! Email RadarOnline.com at tips@radaronline.com.