Ed was about to die. He didn't care anymore. Al's bloodseal had cracked, and he was gone. Father had been killed. Unfortunately, Father had managed to sever one of Ed's arteries before he was killed.
Ed had failed. Al was gone, and even if Ed had a good idea to save him, he was too hurt to act upon it. Ed was ready to curl up and die. He had no reason to live anymore. He might have lived for Winry, but he felt like it was too much to try to stay awake.
He vaguely heard his father shout "Don't leave me son! I already lost your mother, and now your brother." Heh, who cares about that jerk. He already abandoned me before.
Even Mustang was gone. He had made a miscalculation and had accidentally blown himself to bits. Ed wouldn't admit it, but Mustang had started to be like a father to him. Ed was actually sad to see him go.
Edward Elric died that day with the last words, "Sorry Al, I failed."