Justin and Hailey Bieber may not get the fairytale ending they had envisioned.

RadarOnline.com can reveal the celebrity couple’s marriage is hanging by a thread, according to sources who say the model is fed up with her immature hubby moping like a child and dipping back into drugs when they have a baby at home.

Now, insiders say Hailey, 28, is prepared to play hardball if Justin doesn’t mature – going after part of his $300million fortune and seeking custody of their five-month-old son, Jack.

The 30-year-old Peaches singer is allegedly troubled by fears he might be compelled to testify at the upcoming sex trafficking trial of his former mentor, Sean ‘Diddy’ Combs.

Despite the 55-year-old hip-hop mogul’s insistence on his innocence, a source says Bieber is worried that revealing his connections to Combs could “ruin” his career and life.

This has Hailey increasingly concerned about his childish behavior.

Recovering addict Justin, who has admitted to past struggles with alcohol, pills, and party drugs, recently shared startling photos on Instagram from his trip to Aspen, Colorado with Hailey.

In the images, Justin was seen hitting a bong while wrapped in a blanket, exhaling a cloud of smoke.

A tipster said: “Hailey finally agreed to date him in 2015 when he promised to stay clean and sober. He has stuck to that all through their relationship and six years of marriage.

“To see him backslide now – especially since he is a new dad – is absolutely frightening to Hailey. She will leave him before he can sink any further and drag her down along with him.”

The hitmaker has been open about his challenges with severe depression and anxiety. That’s why – according to sources – they were concerned when he swam in an icy Aspen river and lounged in sub-zero temperatures wearing only his tighty-whities.

Another insider claims Hailey has always helped keep her famous husband grounded, but now she’s concerned they’ve reached a crossroads.

They spilled: “Facing the prospect of getting dragged into the Diddy trial has so messed up his mind that he’s acting out.

“Hailey has had it with Justin’s ‘woe is me’ attitude.Their marriage is looking like it cannot be saved.”

Hailey’s top priority, however, is her son, Jack Blues.

She’s reportedly determined to fight Justin for everything to ensure Jack’s future is secure – and to distance herself from him as he potentially spirals deeper into trouble.

Last week, sources told RadarOnline.com the singer could be headed toward another mental breakdown.

They said: “Justin is struggling in a big way. He’s carrying so much baggage right now, and he feels like there’s no way he can lighten the load.

“His recent appearance in New York has really hit home just how fragile he’s becoming. His inner circle are worried and are hoping his problems can somehow go away.”

Justin raised alarms after being spotted in New York City looking gaunt and hollow-eyed, a stark contrast to the fresh-faced, floppy-haired pop star who rose to global fame 16 years ago.

With his head shaved and dressed in loose, disheveled clothes, the performer appeared to be a man weighed down by the world.

Around the same time, divorce rumors swirled as eagle-eyed fans noticed he unfollowed his wife on Instagram – which Justin later claimed was caused by his account being hacked.