What started as a promising on-screen partnership has turned into one of Hollywood’s most bitter legal showdowns.

The once-private feud between actors Blake Lively and Justin Baldoni has erupted into a full-blown public spectacle, with multi-million-dollar lawsuits, shocking allegations and a flood of leaked documents and text messages.

Now, Fox Nation’s new special, “Blake vs. Justin: It Didn’t End With Us,” unpacks the twists and turns of this high-profile battle, offering viewers a deep dive into how these former co-stars became enemies.

Before their falling out, Lively and Baldoni were two of Hollywood’s most likable stars. Lively rose to fame as Serena van der Woodsen on the CW’s “Gossip Girl,” quickly becoming a style icon and fan favorite.

“Every girl wanted to be her,” says pop culture expert Lauren Conlin in the special.

Baldoni, best known for his role as Rafael Solano in “Jane the Virgin,” shifted gears into producing — leading the charge on the highly-anticipated film adaptation of Colleen Hoover’s novel “It Ends with Us,” in which he also starred alongside Lively.

Former “It Ends With Us’ costars Justin Baldoni and Blake Lively, who are now entrenched in a fierce legal battle.  (Fox Nation)

The trouble started when production on the film was halted due to the national writers’ and actors’ strikes. According to legal documents from Baldoni’s team obtained by Fox News Digital, Lively and Baldoni initially had a friendly working relationship.

“They texted almost daily, and a friendly banter established a comfortable dynamic that, under typical circumstances, would have made working together easy,” the document states.

However, tensions escalated during the strike when Lively issued Baldoni a 17-point list of demands she required before returning to set. These included prohibiting “spontaneous improvising” during physical scenes, banning comments about her appearance and restricting discussions about personal experiences with sex or nudity.

“She really sort of put out there that there was something amiss in the workplace, that the workplace was not as safe as one would want it to be,” argues criminal defense attorney Jonna Spilbor in the Fox Nation special.

While Baldoni’s production company, Wayfarer Studios, agreed to Lively’s terms and signed the revised contract, the drama didn’t stop there.

Following the film’s awkward press tour, during which Lively faced heavy criticism, the actress accused Baldoni and his production company of sexual harassment and of orchestrating a smear campaign against her. In her complaint to the California Civil Rights Department, she described a hostile work environment and a coordinated effort to damage her reputation.

Baldoni fired back, denying all claims and launching a counter-suit.

Justin Baldoni included screenshots of alleged text message interactions with Blake Lively in the amended complaint. (Justin Baldoni amended complaint)

In addition to the updated suit, Baldoni shared a timeline of events – including texts and emails involving the actors, intimacy coordinators and producers – as evidence to counter Lively’s claims that she was sexually harassed on the set of the drama where he served as director.

He also filed a staggering $250 million lawsuit against The New York Times, alleging their coverage further harmed his reputation.

With the case still unfolding, “Blake Vs Justin: It Didn’t End With Us” brings together pop culture reporters, legal analysts and familiar Fox News faces to break down the controversy, analyze its implications and explore how this high-profile battle could reshape Hollywood’s future.

Don’t miss the exclusive deep dive premiering Thursday, March 6, on Fox Nation.

Fox Nation special “Blake vs. Justin: It Didn’t End With Us” (Fox Nation)