There are some other covers here, but they don't sound right. Mine might not sound right 
either, but it works for me.

CAPO 1
All chords and tabs are in conjunction to the capo.

"Best I Ever Had"

Little Intro Part:

   Am             C
|--------------|-----0---------|
|------1--0----|----1--3--0----|
|-----2------2-|--0------------|
|----2---------|---------------|
|---0----------|-3-------------|
|--------------|---------------|


Am         F
Now I know I messed up bad
C            G
You were the best I ever had
Am         F
I let you down in the worst way
C           G
It hurts me every single day
Am     F (let it ring)
I'm dying to let you know

Chorus:
C                       G
Now I'm here to say I'm sorry
                      Am
And ask for a second chance
                                    F
Cause when it all comes down to the end
                       Am
I could sure use a friend

Am/F/Am/F (hammer-on the fifth fret 
G-String [haha])

Am       F
So many things I would take back
C            G
You were the best I ever had
Am            F
I don't blame you for hating me
C        G                           Am/F
I didn't mean to make you leave

(You can play this next part 2 ways)

V1:
Am
You and I were living like a love song
F
I feel so bad, I feel so bad that you're gone
Am
Now I know you're the only one that I want
F
I want you back, I want you

V2:
Am             F
You and I were living like a love song
C                G
I feel so bad, I feel so bad that you're gone
Am                    F
Now I know you're the only one that I want
C                  G
I want you back, I want you

C                       G
Now I'm here to say I'm sorry
                      Am
And ask for a second chance
                                    F
Cause when it all comes down to the end
                       Am
I could sure use a friend
C                       G
Now I'm here to say I'm sorry
                     Am
And ask for a second chance
                                    F
Cause when it all comes down to the end
                         Am
You were the best I ever had

(Again there's 2 ways to play this next part.)

V1:
Am                    F
We fell in love for a reason
           C
Now you're leaving
    G
And I just want you back
Am                   F
So many things we believed in
           C           G
Now you're leaving and words won't bring you back
Am             G                 F
I'll never let go of the heart I broke

V2:
Am
We fell in love for a reason
           F
Now you're leaving

And I just want you back
C (Or an Am)
So many things we believed in
           G (or an F)
Now you're leaving and words won't bring you back
Am             G                 F
I'll never let go of the heart I broke

Am             (optional F)
You and I were living like a love song
F (Or C)         (G)
I feel so bad, I feel so bad that you're gone
Am                    (optional F)
Now I know you're the only one that I want
F (or C)          (G)
I want you back, I want you


C                       G
Now I'm here to say I'm sorry
                      Am
And ask for a second chance
                                    F
Cause when it all comes down to the end
                       Am
I could sure use a friend
C                       G
Now I'm here to say I'm sorry
                     Am
And ask for a second chance
                                    F
Cause when it all comes down to the end
                         Am (Or C)
You were the best I ever had

(Okay so you can play the ending 2 ways that didn't sound too bad for me the optional 
chord you can place in use will be in brackets.)

Am (C)
I can't believe that I threw away all our dreams
F (G)
I can't believe now that you're gone how much you mean to me
C (Am)
I feel so bad, I feel so bad
G (F)
You were the best I ever had
Am (C)
I can't believe that I threw away all our dreams
F (G)
I can't believe now that you're gone how much you mean to me
C (Am)
I feel so bad, I feel so bad
G (F)
You were,
                          Am (C)
You were the best I ever had