Fleetwood Mac’s Lindsey Buckingham penned an emotional tribute to “sister” Christine McVie following her “sudden” death on Wednesday. “Christine McVie’s sudden passing is profoundly heartbreaking. Not only were she and I part of the magical family of Fleetwood Mac, to me Christine was a musical comrade, a friend, a soul mate, a sister,” the 73-year-old wrote on Instagram Thursday. “For over four decades, we helped each other create a beautiful body of work and a lasting legacy that continues to resonate today,” he continued, adding that he feels “very lucky to have known her.”