The name Barrymore is one of the most storied in the history of American entertainment. It conjures images of grand theatrical stages, golden-age Hollywood, Academy Awards, and — for those who know the family’s darker chapters — a haunting pattern of addiction and tragedy that has followed the lineage for generations. Within this legendary dynasty lived a woman whose story remained largely untold until her tragic passing in 2014 brought her briefly into the glare of the public spotlight. Jessica Blyth Barrymore — born Brahma Jessica Blyth Barrymore — was the half-sister of megastar Drew Barrymore. She was the daughter…