As Cassie Ventura gets set to testify against Diddy at his federal sex trafficking trial, the former couple once upon a time jetted off to Punta Mita, Mexico for the music mogul’s 48th birthday — and they were filmed having some fun under the sun before their relationship imploded.

TMZ obtained never-before-published footage of Diddy and Cassie in November 2017 at a tropical villa on the private Mexican peninsula.

And get this … the mansion was owned by ‘Girls Gone Wild’ founder Joe Francis until it burned down in 2021 after playing host to a bunch of other celebs, including the Kardashians, Eva Longoria and Ashton Kutcher.

Back to the Cassie-Diddy footage … as you can see, the pair are all smiles as Diddy wraps his arms around Cassie’s bikini-clad body, shimmying their hips to a Spanish song.

In another scene … Diddy and Cassie are learning how to salsa with the help of legendary Choreographer Laurieann Gibson. Cassie busts some moves, extending her arm and placing a hand on Diddy’s shoulder as he does his best to keep up.

Diddy is also captured on video sandwiched between rapper French Montana and Cassie, with the others standing around them singing happy birthday to the Bad Boy Records CEO.

The video ends with the whole group posing for pics with Diddy and Cassie sitting next to each other. What’s interesting is seeing Cassie’s affectionate behavior toward Diddy in this footage, which is in total contrast to how she feels about the man now. Yet, some might say Cassie seems melancholy at times.

As the world knows, Cassie is the star prosecution witness at Diddy’s federal trial, where he faces decades behind bars if he’s convicted of racketeering, sex trafficking and transportation to engage in prostitution, among other offenses.

Kim Kardashian testified Tuesday in Paris, France in the highest profile robbery trial the country has seen in decades … and her account of the heist that claimed $10 million worth of her jewelry was emotional.

Kardashian took the stand Tuesday afternoon and told the court … “I absolutely thought I was going to die.” She described how two men dressed in police uniforms and wearing masks held her at gunpoint … as she wore nothing but a bathrobe, fearing she’d be raped.

The two robbers had overpowered a concierge outside her hotel apartment. They tied Kim up and left her in her bathroom during a Paris Fashion Week visit in October 2016 … then absconded with millions of dollars of loot, including a $4-million engagement ring given to her by her then-husband Kanye West.

Kardashian said … “I kept telling them I have babies and I need to get home to my babies.” She said one of the robbers pointed to his hand and kept repeating the word, “ring.”

One of the men bound her hands and mouth with duct tape, and her ankles with zip-ties. Kim, who was wearing nothing but a bathrobe when the robbers entered her room, revealed … “He grabs by legs and pulls me. I’m naked and my everything is exposed.”

Kim testified … “I was sure that I was going to be raped.” But the men took her possessions and left.

She said she couldn’t remember individual features and faces, due to the trauma of the event. She said, “You start thinking about your family and it all goes out the door.”

In the bathroom, Kardashian said, she managed to remove the duct tape, and scooted out to look for her childhood friend and stylist Simone Harouche, who accompanied her on the trip and was staying one floor below. Harouche helped her remove the remaining zip-ties around her ankles with scissors.

The two then fled outside the Hôtel de Pourtalès and hid in bushes, and she called her mother, Kris Jenner, who has accompanied Kim on this current trip. Police eventually arrived … but Kim said she was confused and suspicious, because the robbers had also been dressed in cop uniforms.

“I didn’t know who to trust,” Kim said today.

Kim testified a French official later told her she’d been targeted by the same robbery ring during a previous visit to Paris … but the gang opted out because Kanye was traveling with her at the time. She said … “That shocked me to find out they’d been trying to plan the attack for some time,” adding she thought the actual heist had been “well planned out.”

The 69-year-old alleged ringleader, “Old Omar,” who is deaf and mute, issued a written statement in court, read out loud today by the judge … asking for Kim’s forgiveness.

“I do appreciate the letter, I forgive you for what has taken place, but it doesn’t change the emotion and the feelings and the trauma the way my life is forever changed,” she said.

Kim discussed how she had always felt safe in the city — prior to the robbery. The trauma has followed her home, as even now in California she keeps 4 to 6 security guards at her house just to feel safe.

Only one item of the stolen jewelry has ever been recovered — a $24,000 diamond necklace a woman found on the street later on the day of the robbery. The necklace had been dropped by one of the robbers fleeing on a bicycle. The woman wore the necklace to work that day, before learning of the heist and turning it over to police.

Nine men and one women — dubbed the “Grandpa Robbers” as most are in their 60s and 70s now — are on trial, which began 2 weeks ago … nearly 10 years after the heist occurred. Many of the suspects were apprehended about 3 months after the robbery.

Cassie’s making her way to court today, about to testify in Diddy’s trial — the first time they’ll lay eyes on each other since 2018.

The pregnant singer — who’s clearly ready to pop with baby No. 3 — departed from an NYC residence and kept her face stoic, but she definitely came to slay — rocking a power camel-colored coat, a brown turtleneck, shades, and boots as she strutted out to the car waiting for her.

Cassie was clearly all business and ready to take the witness stand today. Her attorney, Douglas Wigdor, made that crystal clear when we caught up with him Monday outside the Manhattan federal courthouse where Diddy’s trial is going down.

Cassie’s name came up multiple times during opening arguments and the first day of witness testimony Monday. Prosecutors even claimed Diddy made a male sex worker urinate in her mouth during a “Freak Off’ she was allegedly forced to attend.