Tom Sandoval and Raquel Leviss' Affair Has Been Going on for 6 Months; Ariana Madix 'Devastated'

More light is being shed on the bombshell breakup between Vanderpump Rules stars, Tom Sandoval and Ariana Madix.

Though news broke on Friday that Sandoval, 39, and Madix, 37, had split because the TomTom co-owner allegedly cheated with their costar Raquel Leviss, a source now tells PEOPLE that the affair is nothing new.

"This has been going on for upwards of 6 months — all the while, Tom was sleeping next to Ariana in bed," one source tells PEOPLE. "She was completely blindsided by this; devastated doesn't even scratch the surface of how she feels."

"This is someone she thought she knew; someone she planned to spend the rest of her life with. You can't even put into words that betrayal," the source adds.

Madix was there on Wednesday to see her then-boyfriend's band, Tom Sandoval & the Most Extras, perform in Los Angeles. The two were spotted by onlookers kissing.

"She was supporting his new single," a second insider says. "She had no idea any of this was happening behind her back."

Also on Wednesday, on the other side of the country, Leviss made an appearance with Scheana Shay on Watch What Happens Live with Andy Cohen where she defended her decision to kiss Tom Schwartz, Sandoval's best friend and business partner.

"I'm just trying to live my life and I'm sorry if that offends people but it's not going to stop me from doing what I'm going to do," Leviss said, later giving Andy Cohen a TomTom sweatshirt as a gift.

After the taping, Leviss admitted to Shay the truth about her and Sandoval, a third source tells PEOPLE.

"Scheana was furious," the source says. "She and all the Vanderpump Rules costars have rallied around Ariana during this time. They can't believe Raquel would do something like that."

Meanwhile, Madix herself learned about Leviss and Sandoval's alleged affair at the venue on Wednesday when a selfie video sexual in nature from Leviss popped up on his phone.

She then began scrolling and saw their history of inappropriate texts. Madix and Sandoval exited after his performance wrapped.

"Ariana had been there for Raquel when she went through her split with James. She thought they were friends," the second source says. "This isn't something you do to a friend."

A fourth source told PEOPLE earlier on Friday that Madix and Sandoval had been having problems "for awhile" but that learning of this "was the final straw for Ariana" after nine years together.

"She put up with a lot over the years, but she won't sit back and be disrespected this way," the insider said.

Madix, Leviss and Sandoval could not be reached for comment, and have not publicly addressed the allegations.

Viewers hoping to see this play out on the Bravo show are in luck. A source close to production shares that "cameras are rolling right now" on Vanderpump Rules so Madix and Sandoval's split will be shown in season 10, which is airing now.

Film crews even caught a tense sit-down between Madix and Sandoval at their home Friday afternoon, where they discussed their split and the fallout of the alleged affair. Photographers also captured Sandoval packing his bags into a car outside of their shared home on Friday, shortly after the reports broke.

Cameras are expected to stay up through the weekend to capture the rest of the cast's reactions — though they've been sharing many of them on social media.

Leviss' ex- fiancé James Kennedy responded to the news on Instagram, writing, "Hope you all feel as sick as I do. This explains everything."

Lala Kent chimed in too, writing in part: "Everyone said I was a 'bully'. It's called YOU TRIGGER ME AND I SEE YOU FOR WHO YOU ARE! I've known these two are disgusting from the jump."

"I've seen you for who you [are] for a long time, and you just don't like that," she said of Sandoval. "But, I think now is the time for you to shut the f--- up. I'm eating good the next time I see you."

Of Leviss, she wrote, "I suggest you get some energy for me. You're gonna need it."

Before the cheating scandal was revealed on Friday, Leviss attracted headlines for hooking up with costar Katie Maloney's ex-husband Schwartz at Shay's wedding. The storyline was already teased in the season 10 VPR trailer.

Vanderpump Rules airs Wednesdays at 9 p.m. ET on Bravo.