Kyle Richards and Kathy Hilton Are 'Still Not Speaking,' Says Source: 'Nobody Has Made an Effort'

Michael Kovac/Getty Images for Elton John AIDS Foundation Kathy Hilton and Kyle Richards at Elton John's Academy Awards Viewing Party

Things still aren't hunky dory between sisters Kyle Richards and Kathy Hilton.

A source tells PEOPLE that the siblings and Real Housewives of Beverly Hills costars are "still not speaking" following the show's reunion and Hilton's meltdown during a season 12 cast trip to Aspen last year.

"Nothing has really changed since the reunion. They're still not speaking. Nobody has made an effort to sit down and patch things up," the source added. "Kyle is busy focusing on herself right now and Kathy is doing the same. But they're family and each of them are supportive of the other and always will be."

The sisters posed for a picture together at Elton John's 31st Annual Academy Awards Viewing Party in Los Angeles on Sunday, but they sat on separate tables with RHOBH castmates including Crystal Kung Minkoff and Lisa Rinna and Diana Jenkins, who both exited the show after season 12).

RELATED: Garcelle Beauvais Gives Update on Filming of RHOBH as Season 13 Is Underway: 'Expect Drama'

Araya Diaz/WireImage Kathy Hilton and Kyle Richards

The insider also tells PEOPLE that Hilton — who joined the cast as a Friend in season 11 — still hasn't decided whether she will join season 13 filming for the Bravo series, which is currently underway.

"Kyle is waiting like everyone else to see if she ends up doing the show," the source added.

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In December, the pair both opened up about the status of their sisterly relationship and sibling rivalry at the People's Choice Awards.

"I have not talked to [Kyle] in a while," Hilton, 64, told Access Hollywood. "We've texted, but I have not talked to her for a while."

Richards, 54, told Extra: "We could be better, but we are sisters and at the end of the day we always come together, but we could be better and that's what I want, that's what I need in my life — to feel good."

Nicole Weingart/Bravo/NBCU Photo Bank via Getty

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The tension between the duo stems back to filming in Aspen. While the on-air drama (which aired in September) mostly happened mostly off screen, Rinna and her fellow cast members recounted Hilton having a meltdown after Rinna began drinking Kendall Jenner's 818 Tequila over Hilton's Casa Del Sol tequila (in which she and her daughters Paris Hilton and Nicky Hilton Rothschild are investors) and wouldn't join her conga line.

Hilton became upset at Richards for not defending her after Rinna's apparent snub and left the group. Hilton could be heard saying "too f---ing disgusting," as she walked away. She added, "I am f---ing pissed off!"

Rinna, 59, then took Hilton home. "We get in the sprinter van and Kathy starts screaming about everything, and she'd say things like, 'I'm gonna take down NBC, Bravo, I will take down the show single-handedly. I will f---ing ruin you all!'"

Rinna continued, "She takes her glasses off, she throws them on the ground, she's jumping up and down, breaking her glasses, she's pounding the walls and she's screaming she 'made' Kyle… Kathy's responsible for Kyle and she said, 'I will destroy Kyle and her family if it's the last thing I ever do.'"

bravo Kathy Hilton and Lisa Rinna

RELATED: Kathy Hilton Calls Lisa Rinna the 'Biggest Bully in Hollywood' as Kyle Richards Pleads to Leave RHOBH Reunion

Things then came to a head during the RHOBH season 12 reunion, which aired in October and left Richards in tears and a rekindling of their relationship uncertain.

It's not the first time the fate of Richards' and Hilton's relationship has been uncertain.

The family drama between the pair and their sister and former RHOBH star Kim Richards, 58, is long-running — but only since the Bravo show started airing in 2010 has the tension between the three sisters become public knowledge.

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The Real Housewives of Beverly Hills can be streamed in full on Peacock.