Jessica Chastain has confirmed that she's joined the cast of X-Men: Dark Phoenix. It had been rumored that she was in negotiations to play the villain Lilandra of the Shi'ar Empire -- the on-again, off-again true love of Charles Xavier. Chastain confirmed her role on Instagram by teasing Professor X actor James McAvoy with the caption, "You ready for me up in Montreal? Im gonna make you cry so hard."