I couldn’t believe that my sister was dead. Why did my sister do such a horrible thing?

          Two days before I had seen my sister strange, she was scared and nervous. The night before the accident she went out, she said to me that she was going to the graveyard to visit the tomb of some friends that died in the war. She went to the graveyard with her best friend Lucia. When I told her that my sister was dead she said that she must talk with me in person about the night in the graveyard.

          What happened that night in the graveyard? What made my sister decide to drive the car off the bridge?