Kelly Clarkson ‘devastated’ for her kids after ex-husband death

However, “Kelly’s biggest fear during the divorce was that her kids would grow up feeling distant from their father,” revealed the source.

“She always wanted to spare them that. She’s devastated for them …”

As Page Six previously reported, Clarkson was by Brandon’s side as he fought a three-year battle with melanoma, a severe form of skin cancer, even taking time off her hit NBC talk show.

“Even though things were not good with her and Brandon for a while before they split — and then they got positively nuclear during the divorce proceedings — absolutely none of that ever changed Kelly’s bottom line: her kids deserved to grow up having a wonderful relationship with their dad,” said the source.

Audience members reported that the singer broke down in tears as she performed her hit “Piece by Piece” — a song she wrote about her dad and her ex — at her last Vegas show the weekend before Blackstock’s death. Video shows her telling the crowd, “I’ve never rewritten a song more and I probably never will,

“I wrote this song with a lot of hope and projection for happiness and better than what was happening. And then, well, life set in and I had to change the lyrics. Everybody was like, ‘Wait, why aren’t you singing this song?’ And I was like, ‘Have you heard the lyrics?’ That’s fun. Embarrassing.” 

As she tried to go on, Clarkson once again got emotional, saying, “I’m really trying to pull it together,” before introducing the song by declaring, “Screw it, let’s just sing it. This is ‘Piece by Piece.’ “

The star got primary physical custody of the children in the divorce and shared joint legal custody with Blackstock. She has been living with River and Remy in NYC, where she tapes “The Kelly Clarkson Show.”

Clarkson grew up in Burleson, Texas, with her mom, schoolteacher Jeanne Taylor, with whom she’s extremely close.

“Kelly has had a very strained relationship with her own father her entire life,” said the source, “They are essentially estranged, and when she and Brandon first got together he had stressed to her how important it was that his relationship with his kids remained strong. Their bond wasn’t going to end just because that marriage did.”

Talent manager Blackstock, who died at 48 last week, also had two children — Savannah, 23, and Seth, 19 —from his first marriage, to Melissa Ashworth.

“For all their issues once they split — and it was really really toxic and bad— Kelly really did learn from what she saw from Brandon in their first days together: He never badmouthed his first wife around his kids, and he never let that divorce get in the way of their bond,” the source said. “So Kelly knew she would do the same thing.

“She wasn’t going to be the reason why her kids weren’t close with their dad.”

Speaking of River and Remington, the source added, “[Blackstock’s death] will change them forever, and it’s a tragedy that has just wrecked [Clarkson].

“Brandon didn’t turn out to be the best husband for her or the best person to try to separate from easily or amicably, but he was always very good dad who adored his kids. She will grieve that particular loss forever.”

Clarkson is due back on the set of “The Kelly Clarkson Show” next month, but the fate of her appearance as a returning coach on “The Voice” is up in the air, sources said.