Elon Musk’s first wife has spoken up about the billionaire’s account of their first-born’s death, claiming it was her, not him, who held their 10-week-old son Nevada in her arms as he was taken off life support. Justine Musk, who shares five children with the tech CEO, took to Twitter after Musk used Nevada’s death to explain his reasoning for keeping Sandy Hook denier Alex Jones off the social media site. “My firstborn child died in my arms. I felt his last heartbeat,” Musk tweeted last week. “I have no mercy for anyone who would use the deaths of children for gain, politics or fame.” But three days later, his ex-wife, who wrote publicly about the loss last year for Marie Claire, responded to someone who asked if her son died of SIDS. “A SIDS-related incident that put him on life support. He was declared brain-dead,” she wrote. “And not that it matters to anyone except me, because it is one of the most sacred and defining moments of my life, but I was the one who was holding him.”