In a film from Christian group I Am Second, Duck Dynasty's Phil Robertson and Miss Kay open up about Phil's pre-fame bout with alcohol and infidelity Credit: Karolina Wojtasik

Duck Dynasty's Robertson family may be flying high now, but they've had their fair share of low moments in the past. In a new film from the Christian group I Am Second, patriarch Phil Robertson and his wife, Miss Kay, open up about their pre-fame struggles with Phil's alcohol problems and adultery, which very nearly destroyed their marriage. 

"The drinking got worse," Miss Kay says in a teaser for the 30-minute movie, titled simply The Robertsons. "And I knew then, but I didn't want to believe it -- he was running around on me. And what I would tell my boys all the time is, 'That's not your daddy. That's the devil in your daddy.'" Later, she adds, "I've been fighting for this marriage for a long time."

Phil, for his part, admits he let his behavior get out of control. "I got in a big barroom brawl," he recalls. "The laws got after me." And that wasn't even the worst part. "I would say the low point was when I ran Miss Kay and the kids off," he says.

Kay -- who married Phil when she was 16 and went on to bear kids Alan, Jase, Willie, and Jep -- previously told Us Weekly she wasn't sure their marriage could be saved. "It got about as bad as it can get," she shared with Us.

They hit bottom, she said, when Phil accused her of cheating on him. "For him just to say that...I think that's the most hopeless feeling I had," she recalled, noting that she actually briefly considered taking her own life at that point. "[I felt] like I could not save this marriage, I couldn't save him. I was obviously not feeling like I could rise above it."

Fortunately for Phil, she did -- and now their marriage is stronger than ever. "I think that I just believed he was the one from the very, very start -- from the first time, I knew it -- and when I gave myself to him, that was it," she told Us of not giving up on him. "It was for life, and I would do everything and fight for 10 years [to save the marriage], and that’s what I did."