There are only four main chords used throughout the whole song 
if you listen carefully to the acoustic version of this awesome song.
You gotta figure out the strumming pattern youself

[G]  3 5 5 4 3 3
[B]  7 9 9 8 7 7 
[B#] 8 10 10 9 8 8
[Cm] 3 3 5 5 4 3

[G] [B] [B#] [Cm] It comes in only in certain verses
example:

When you were [G] here before
Couldn't look you [B] in the eye
You're just like [B#] an angel
Your skin makes [Cm] me cry

goes on .....

Hope you'll enjoy it!