Remus wakes from the full moon alone and devastated to learn that Sirius told Snape how to bypass the Whomping Willow, nearly exposing Remus's werewolf secret and potentially causing deaths. James managed to stop Severus just in time, but the damage is done. Remus feels utterly betrayed by his best friend and makes the devastating decision to never forgive Sirius, cutting off all communication despite Sirius's desperate attempts at reconciliation.