Marine Staff Sgt. Aaron White was killed in a helicopter crash in Iraq. Here is an excerpt from his last letter home to his wife. "What keeps me up at night is thinking you may never know what you mean to me. . . . If I don't come home, please tell Brianna that her daddy loves her more than life. . . . Brianna, it breaks my heart to have to miss your first birthday. I hope that you will forgive me. . . . Aaron was killed two days after Brianna turned 1. A just-released study by the...