Sean “Diddy” Combs once hurled a knife that came “pretty close” to hitting his then-girlfriend Cassie Ventura — and dangled her friend over a 17th-story balcony as he raged “You know what the f–k you did,” according to dramatic testimony Wednesday.

Bryana “Bana” Bongolan — a close friend of Ventura’s — recounted the harrowing ordeals as she took the stand at Combs’ high-profile sex-trafficking and racketeering conspiracy trial in Manhattan federal court.

In one particularly frightening incident, Bongolan told jurors that she’d been sleeping on Ventura’s couch in Los Angeles when the Bad Boy Records founder started banging on the door.

After asking Combs to leave, Bongolan – who was five-foot-one and weighed 100 pounds — testified that he followed her out onto the balcony.

“He basically came up from behind me,” she recalled. “He lifted me up and hung me off the rail.”

During the 10 to 15 seconds while Combs was allegedly manhandling her, he screamed: “You know what the f–k you did.”

Bongolan, who insisted she still doesn’t know what the disgraced music mogul meant, said he then tossed her onto the balcony furniture.

Jurors were shown photos of the balcony and also an image of a leg bruise Bongolan apparently sustained during the September 2016 ordeal.

Elsewhere during her testimony, Ventura’s pal recalled a time when Combs threw a knife at his then-girlfriend.

Bongolan, who was again staying at the R&B singer’s LA apartment, said she woke to find an “upset” Combs inside.

The “I’ll Be Missing You” rapper then took out a blade and pointed it toward his girlfriend before he “threw the knife in Cassie’s direction,” Bongolan testified.

She said the knife came “pretty close” to where Ventura was standing but didn’t strike her.

Bongolan, who had earlier noted the couple had a “volatile” relationship, said Ventura “threw the knife back.”

Combs, who wasn’t struck, then “left quickly,” Bongolan testified.

She detailed, too, another scary run-in she had with Combs that saw the rapper get up in her face while she was in Malibu doing a photoshoot with Ventura in 2016.

“He came up really close to my face and said something along the lines of ‘I’m the devil and I could kill you,'” Bongolan said.

She added that she didn’t know why Combs made the chilling threat and couldn’t tell if he was on drugs at the time.

“I was terrified,” Bongolan said, admitting that she was on cocaine at the time.

Combs and Ventura dated on-and-off for about a decade before breaking up in 2018.

Ventura, 38, testified for four grueling days earlier at the trial, including about the powerful producer allegedly raping her following their split.

Combs, 55, is on trial for allegedly using his fame, fortune and many businesses to run a decade-long scheme in which he controlled and manipulated Ventura into drug-fueled “freak-off” sex marathons that went on for days.

The disgraced rapper, who has pleaded not guilty, faces life in prison if convicted.