Hush now, I'm here

Sirius arrives in Godric Hollows to find that he is too late: his best friend and his family is gone. Dead all because of him. He cries out his sorrow over his fallen friend when he hears a cry, almost as a response to his own. He runs upstairs, to find the corps of the dark lord, and his godson, alive and scared. What is he suppose to do now?