Brandon Blackstock learned he had cancer after his divorce from Kelly Clarkson, sources tells PEOPLE exclusively, then moved back to Montana following his diagnosis. The former music manager died in Thursday,

The family of Kelly Clarkson’s ex-husband, Brandon Blackstock, is beginning to speak out after his tragic death at age 48. Brandon died on Thursday, August 7, after a private, yearslong battle with cancer. His brother, race car driver Shelby Blackstock, 35, was one of the first in the family to publicly address his passing.