Aang's Sister

Running from heartbreak, Avatar Aang just ended the hundred year war. But instead of celebrating, his heart was just shattered by the girl he loves. He heads off to find the very rumored Eastern Air Temple, he is hopping that the Fire Nation didn't destroy it, for it was only rumored about among the Air Nomads. What will happen if Aang finds out he has a twin sister and that other air benders survived Sozins Commet?