Brandon Blackstock and Kelly Clarkson attend the Critics Choice Awards in Santa Monica, Calif., Jan. 12, 2020. (Frazer Harrison/Getty Images)Brandon Blackstock, Kelly Clarkson's ex-husband, talent agent and her former manager, has died after a battle with cancer, his family announced on Thursday. He was 48."It is with great sadness that we share the news that Brandon Blackstock has passed away," a representative said in a statement to multiple news outlets. "Brandon bravely battled cancer for more than three years. He passed away peacefully and was surrounded by family.