Twilight question: clair de lune

So I've forgotten what tie Clair de Lune has to Twilight. I only know that every time I hear it, I cry. I am a devoted Twilight fan, and trust me, I am very angry with myself for forgetting. ;-)
Any help?

im a huge twilight fan to! but I don't know what that has to do with twilight

oh wait I think I no! one of the times that they were in the car Edward was listening to a song but that person and I thinkit was bout vampires sort of because the title of the song was something blood so yeah

It was played when Edward was showing Bella his room and Bella turned on the cd player to see what kind of music Edward was listening to. He said Debussy, the music played for a minute, and Bella said Clair De Lune is great.

when Bella and Edward were in Edwards room Bella turned on his CD player and Clair De Lune was playing. Edward said that it was Debussy and Bella said the title, Clair De Lune, because she heard it when she lived with her mom

...also Clair De Lune means light of the moon or moonlight in english