I think think that the lyrics from songs like O, Fix You and The Scientist are 100% heart wrecking. I remember that famous interview last year with Zane Lowe in which he was playing O and at some point he makes a question to Chris and his voice breaks and I just...nearly DIED, I mean, you could literally hear my heart breaking. Though I think I would choose 2 lyrics:
If you love me, won't you let me know?/I don't wanna be a soldier who the captain of some sinking ship would stow/if you love me, why d'you let me go?- Violet Hill (I can totally relate to this song)
Might have to go where they don't know my name, floaf all over the world just to see her again and I won't show or feel any pain- Up With The Birds (I used to dislike this song, then I read these lyrics and I fell in love).