Kelly Clarkson is "staying strong" for her kids following Brandon Blackstock's passing

A source told People: "Kelly and Brandon had their ups and downs, but at the end of the day, he was the father of her children and she is absolutely heartbroken for them. Her kids are her entire world, and she's staying strong for their sake."

Brandon - who had River, 11, and Remington, nine, with Kelly - served as the pop star's manager during their marriage. And despite their acrimonious break-up, Kelly always tried to remain "classy" for the sake of their kids.

The insider added: "When she found out that he was sick, she remained protective of him for their sake.

"Kelly has always tried to keep things classy. It became clear earlier this year that Brandon was not doing well. She's been devastated for the kids."

Brandon's death was announced on Thursday, with a rep telling People that he was "surrounded by family" when he passed away.

The statement read: "It is with great sadness that we share the news that Brandon Blackstock has passed away.

"Brandon bravely battled cancer for more than three years. He passed away peacefully and was surrounded by family.

"We thank you for your thoughts and prayers and ask everyone to respect the family's privacy during this very difficult time."

Brandon's passing was announced shortly after Kelly postponed her Las Vegas residency in order to spend more time with their children.

The 43-year-old pop star - who was married to Brandon between 2013 and 2022 - wrote on X: "Unfortunately, I need to postpone the remainder of the August Studio Session dates in Las Vegas.

"While I normally keep my personal life private, this past year, my children's father has been ill and at this moment, I need to be fully present for them."

The pop star revealed at the time that Brandon was ill, although she didn't share any other details about his sickness.

Her post added: "I am sincerely sorry to everyone who bought tickets to the shows and I so appreciate your grace, kindness and understanding."