'RHOBH' Relapse? Kyle Richards Fears Pill-Popping Kim Is Back On Xanax, Insider Claims

Is Kim Richards really still sober? The Real Housewives of Beverly Hills star recently admitted to popping her ex-husband Monty's cancer pain medication, but RadarOnline.com has learned that her sister Kyle isn't buying it. Instead, insiders tell Radar, Kyle fears she's been using Xanax!

Viewers were shocked during Tuesday night's episode of RHOBH as recovering alcoholic Kim copped to taking a pain pill belonging to her ex-husband Monty, which resulted in a bizarre meltdown during her co-star, Eileen Davidson's poker party.

However, insiders say Kim's sister Kyle believes the rehab vet "wasn't telling the truth about what she actually took that caused her to act so unlike herself. The idea that Monty, who is currently living with Kim, would just randomly give her a pill that wasn't prescribed to her just doesn't make sense. Kyle fears she was taking Xanax."

But she didn't confront her while the cameras were rolling.

Said the source, "The only thing Kyle was trying to do during Kim's on-camera meltdown was minimize the behavior. She was trying to protect Kim from looking really bad and making a fool out of herself."

Now, even though filming was completed months ago, the sisters are still continuing to feud. Kim skipped Kyle's, birthday lunch in January, as they deal with the fallout of Kim's pit bull Kingsley's vicious attack on Kyle's daughter, Alexia.

While the sisters have had their differences over the years, "It's just not a very good time for them, and there might not be any way to get over it," the insider added.