Kelly Clarkson abruptly cancelled her Las Vegas shows, announcing that her ex-husband, Brandon Blackstock, was ill. Then, came the tragic news that Blackstock was dead at the age of 48. What was his cause of death?

Many of Kelly Clarkson’s fans likely remember Brandon Blackstock for fighting with the American Idol alum over their Montana ranch during their divorce and, while the couple certainly went through some contentious times,

Kelly Clarkson's "staying strong" but is "heartbroken" for her kids after ex Brandon Blackstock's death, a source tells PEOPLE. The singer and her late ex-husband share daughter River, 11, and son Remington,