Kelly Clarkson Realized 'This Isn't Happiness' During Marriage to Brandon Blackstock

Add Kelly Clarkson to the list of celebrity fans of Glennon Doyle's Untamed.

On Tuesday, the singer, 38, had the author on her daily NBC talk show to discuss the beloved book, which follows the dissolution of Doyle's first marriage to Craig Melton and how she found love with soccer star Abby Wambach.

"Glennon, you write about the fallout from your divorce — I'm obviously going through one right now," said Clarkson, who filed for divorce from estranged husband Brandon Blackstock in June after seven years of marriage. "It's horrible. There are so many hard parts. The hardest for me is the kids ... I think, as women especially, we're trained to take it all on and deal with it and you're fine. But it's your babies that you worry about."

Clarkson — who shares daughter River Rose, 6, and son Remington Alexander, 4, with Blackstock, 43 — then asked Doyle, 44, what she thought the hardest part of getting through a public divorce was, and she agreed, "It's always the kids."

"We're trained to believe to avoid at all costs a broken family," Doyle said, adding that she stayed in her first marriage until she realized, "Oh my God, I'm staying in this marriage for [my daughter], but would I want this marriage for her?"

"We've all been trained to believe a good mother is a liar," she continued. "I didn't leave a marriage in spite of being a good mother; I left because I am a good mother."

RELATED: Brandon Blackstock Seeking $436K a Month in Spousal & Child Support in Kelly Clarkson Divorce: Source

That line in particular hit home for Clarkson, who said, "That's what I needed to see to make a step in my own life."

In her marriage to Blackstock, Clarkson said she realized, "This isn't happiness, and we both deserve better. That line so hit home for me: I don't want this for everyone in this scenario right now."

On Monday, PEOPLE confirmed that Clarkson was awarded primary physical custody of her and Blackstock's two children.

"The Court finds that under the circumstances present in this case, the interest in providing stability and continuity for the minor children weighs in favor of Petitioner having primary custody," the court document read, referring to Clarkson.

The document added that "the level of conflict between the parents has increased. The parties have a difficult time co-parenting due to issues of trust between them."

A source previously explained to PEOPLE that Blackstock, a music manager, wanted the children to go "back and forth" from Los Angeles to Montana or reside in Montana even though L.A. — where Clarkson works — has "undeniably been their home base."

In late October, the court found that the children "have not resided in Montana" and instead Blackstock must travel to L.A. to see the children at Clarkson's Woodvale residence for "visitation and parenting time" on alternate weekends.

RELATED VIDEO: Kelly Clarkson Awarded Primary Physical Custody of Kids amid Brandon Blackstock Divorce

Clarkson has previously addressed her divorce on The Kelly Clarkson Show, saying in September that she "didn't see" it "coming."

"Definitely didn't see anything coming that came, but what I'm dealing with is hard — it involves more than just my heart, it involves a lot of little hearts," she said.

"We know the best thing here is to protect our children and their little hearts," she added then. "So I'm usually very open and I usually talk about everything but in this case I will talk a little bit here and there about how it affects me personally, but probably won't go too far into it because I'm a mama bear and my kids come first."