Alex Arredondo, a Marine killed in Iraq, once wrote: “I am not afraid of dying. I am more afraid of what will happen to all the ones that I love if something happens to me.’’ Grief-stricken by Alex’s death, his father, Carlos, climbed into a van that burst into flames in what he called an accident. Miles away, his other son, Brian, watched on TV. “I just want to die,’’ he told his mother. On Dec. 19, more than seven years later, he took his life.