This is Shake it out, originally sang by Florece + The Machine.
I really like Glee's version so here it is for you all!
So this is the short version they sing on the show :)

capo on 3

( D )
Regrets collect like old friends
Here to relive your darkest moments
( G )
I can see no way, I can see no way
( D )
And all of the ghouls come out to play

Bm          G                     D
And every demon wants his pound of flesh
              A                     Bm
But I like to keep some things to myself
           G             Em
I like to keep my issues strong
             G
It's always darkest before the dawn

D
And I've been a fool and I've been blind
                              G
I can never leave the past behind
I can see no way, I can see no way
D
I'm always dragging that horse around

Bm               G                            D
And our love is passed, it's such a mournful sound
                   A                       Bm
Tonight I'm gonna bury that horse in the ground
              G              Em
So I like to keep my issues strong
                 G
But it's always darkest before the dawn

D
Shake it out, shake it out, shake it out, shake it out, ooh woaaah
Shake it out, shake it out, shake it out, shake it out, ooh woaaaah

G
And it's hard to dance with a devil on your back
              D
So shake him off, oh woah

Bm                             G
And it's hard to dance with a devil on your back
D                                  A
And given half the chance would I take any of it back
Bm                          G
It's a final mess but it's left me so undone
Em            G                D
It's always darkest before the dawn

Bm                            A
Looking for heaven, for the devil in me
Bm                            A
Looking for heaven, for the devil in me
G
Well what the hell I'm gonna let it happen to me

D
Shake it out, shake it out, shake it out, shake it out, ooh woaaah
Shake it out, shake it out, shake it out, shake it out, ooh woaaah

G
And it's hard to dance with a devil on your back
D
So shake him off, oh woah

D
Shake it out, shake it out, shake it out, shake it out, ooh woaaah
Shake it out, shake it out, shake it out, shake it out, ooh woaaah
G                 D

End!