Kyle breaks down on Tuesday's "RHOBH" reunion when she reveals why her relationship with her sister is so strained.
"'American Woman' is inspired by my life growing up with my mom in the '70s," Kyle said. "When I'm with my sisters, 'American Woman' doesn't usually come up. I feel like, since the beginning, they didn't really understand what the project was. It's not exactly our life at all."
Even though Kyle has repeatedly said the show is "inspired by" and "not based on" her life with her mom, her sisters -- Kathy Hilton and Kim Richards -- have not shown any interest in the progress of the project. In fact, it's caused quite a rift in Kyle's relationship with Kathy specifically.
"Is their issue that they feel it's their story to tell and not just yours?" Andy Cohen asked Kyle.
"No, because it's not exactly like our life," Kyle replied. "There's two sisters in the show, not three. And the writers take creative license. That's why I kept saying, 'inspired by, inspired by,' not 'based on.' I think they thought it was more literal. I would never take the liberty to take someone else's story, ever."
When Andy asked how Kyle's relationship with Kathy was, she hesitated, then said, "Not great." When Andy asked when the last time they spoke was, Kyle said, "Maybe 6 months ago."
Lisa Vanderpump chimed in and said she ran into Kathy the night before.
"If your mother was alive, I think then the cohesion would have pulled them back together," Lisa said. "And I think now the mother's not part of the equation, and honestly, that's what Kathy said to me last night."
But "American Woman" wasn't the catalyst of the demise of Kyle's relationship with Kathy. Kyle admitted there's been tension since her husband, Mauricio Umansky, broke away from Rick Hilton to start his own real estate business. Kyle got emotional when she said the split affected "the family dynamic," and now, she and Mauricio "don't always get invited over for Christmas."
But Kyle's hopeful that "American Woman" will help reignite a line of communication between her and Kathy. She said that despite the family tension surrounding "American Woman," she's excited for its debut so that her sister can see that it's very different from what she's been imagining.
"I'm looking forward to her seeing 'American Woman' because I think she's gonna look and say, 'I read the situation wrong,'" Kyle said. "And then we'll go from there."