Actress Kristen Stewart has opened up about playing Princess Diana in upcoming biopic Spencer, admitting it’s “one of the saddest stories to exist ever.” Speaking about stepping into the iconic late Royal’s shoes in the anticipated movie, Kristen explained that she desperately wants to do Diana and her lasting legacy justice.The 31-year-old former Twilight star told In Style Magazine: “It’s one of the saddest stories to exist ever, and I don’t want to just play Diana — I want to know her