Christine Brown appears happily married to husband Kody on Sister Wives, but behind the scenes the third wife is “miserable.” In an exclusive interview with Christine’s aunt Kristyn Decker, she is begging her family member to leave the “cult-like” and “abusive” marriage.

Kristyn, who is the author of Fifty Years in Polygamy: Big Secrets and Little White Lies, grew up in polygamy and escaped 33 years after she married her first husband. Now that she is happily in a monogamous marriage, she is calling on her estranged niece Christine to do the same.

“I was still in polygamy when Christine joined,” she said. “She looked happy. I thought, ‘She’s crazy about Kody, so go for it!’ Even as a believer, I wanted to privately to go tell them to run. I knew how crazy and insane it was. You don’t know what you’re getting into. I wish I would’ve warned people.”

Kristyn explained how she feared she would “be held accountable and go to hell” if she left or warned people from joining plural marriages, as that is what the church teaches.

“It’s a miserable-happy life,” she explained. “The Browns are miserable-happy. They’re miserable on the inside. I don’t think any of them know what genuine happiness and freedom is. I thought I was happy. I thought life was great and I was serving God. I was happy serving God, but miserable doing it. The more you sacrifice, the better your blessings will be in heaven.”

Although Kristyn appeared on Sister Wives, the family members are now estranged.

“We have not been in touch,” she claimed. “I’ve been the bad apple to speak against polygamy. I would speak to [the Browns] anytime, but I don’t believe they want to speak to me.”

As for helping Christine leave Kody, she explained, “If she’s not ready, that would be the worst thing. I’m here for her if she never needs somebody.”

But she explained how it would be difficult for Meri, Janelle, Christine and Robyn to leave Kody with the show involved.

“If there were no show, there would’ve been a bigger chance for them to leave,” the author explained. “That’s their income! All the parties, traveling… none of that would’ve happened without the show.”

Scroll down RadarOnline.com’s gallery to go inside the “cult-like” and “abusive” marriages.