Kyle Vs. Kathy: Feud Intensifies Over Playboy Millions

The sister feud between Kyle Richards and Kathy Hilton has only intensified since their husbands' real estate firms have been given the Playboy Mansion as a listing and RadarOnline.com has the exclusive details about their bitter battle.

"Kathy and Kyle are still not on speaking terms," a source told RadarOnline.com about the sisters. "These two sisters are so stubborn that neither one is going to back down and reach out to the other one."

The siblings' feud is centered on the husbands, Rick Hilton and Mauricio Umansky, who worked together at the prestigious Hilton & Hyland firm. As RadarOnline.com previously reported, Richards' hubby grew disgruntled with never being made a partner and started The Agency, which became a hugely successful real estate company.

But the two firms were hired to sell Hugh Hefner's famed Playboy Mansion, putting it on the market for a whopping $200 million. "The sale is strictly business and it isn't technically split, it is whichever place actually sells it gets the commission," an insider told RadarOnline.com.

While the two firms are battling to bring in the buyer, the source told RadarOnline.com that the sisters' husbands are staying out of the situation. "Rick and Mauricio don't have to interact."

"Family dynamics can be very complicated and my family can be no exception," Richards said on a recent episode of the Real Housewives of Beverly Hills.