Of Werewolves and Wizards

At the first full moon of their sixth year, Sirius lets slip where Moony goes during the full moon. How does Remus come to terms with Sirius' betrayal? What if Dumbledore had learned about the animagus? What if Dumbledore had discovered the steps Lord Voldemort took to ensure immortality during the Marauder era? How would that have changed their lives? Wolfstar and AU.