Novelist and literature professor Philippe Claudel makes his directorial debut with the powerful yet subtle “I’ve Loved You So Long,” about secrets and the possibility of being reborn. In perhaps her most nuanced and soulful film performance to date Kristin Scott Thomas sets the tone for the story that focuses on two long estranged sisters who are trying to reestablish a relationship. Smart, intense, psychologically textured, and clearly written with a novelist’s eye, “I’ve Loved You So Long” (to be released by Sony Pictures Classics on October 24) is a story about the power of forgiveness and the universal need to reach out beyond ourselves.