Kelly Clarkson has “been devastated” for her kids River, 11, and Remington, 9, as their dad Brandon Blackstock, who died on Thursday, Aug. 7 at age 48, faced cancer for three years privately, a source tells PEOPLE exclusively.

The 'American Idol' alum has two beautiful kids with her ex-husband Brandon Blackstock, and despite their divorce, they've put their children first.

Brandon Blackstock, the late ex-husband of singer Kelly Clarkson, was a father of four. The talent manager died on August 7 after a private cancer diagnosis. Blackstock was 48 years old. “It is with great sadness that we share the news that Brandon Blackstock has passed away,