By Li Cohen February 18, 2021 / 7:14 AM / CBS News Demi Lovato is opening up about the grim and painful realities of suffering from addiction and mental health conditions. In a trailer for her new YouTube docu-series, released Wednesday, Lovato revealed that the overdose she experienced in 2018 caused her to have three strokes and a heart attack. "I've had so much to say over the past two years wanting to set the record straight about what it was that happened," the actress and singer said at the beginning of the trailer. The four-part documentary, "Demi Lovato: Dancing with the Devil," focuses on Lovato's personal and professional life leading up to and after the overdose she experienced in July 2018.