Not sure on the Chorus riff but pretty confident the chords are correct.

So Long
Fischer Z

Intro: C G F F C G F F

C                         G                          F
When I read your letter I coudn't believe that you'd gone.
C                         G                   F
I dialled your number but no one answered the phone
G                                  F
I asked your friends to tell me if they knew where you were,
G                                    F
They said they thought that you were ill.

Break: C G F F C G F F

C                      G                         F
I hired a detective to try and find out where you are.
C                        G                          F
He managed to trace you, he said you were living in France.
G                             F
A watchman saw you climb into someone elses car
G                             F
And drive off laughing in the night.

Chorus
F                   C
Why didn't you tell me. 
F                 C
Not leave me this way.
F                   C
You could have told me 
F                 C
Not waited for so long.

I've tried to forget you but I find myself walking the street.
I went to the doctor and he gave me something to sleep.
I sent you telegrams but you haven't aswered one.
Your mother told me I best leave you well alone.
I hope your satisfied now you've done this thing to me.
I hope you're pleased with what you've done.

Chorus
Why didn't you tell me. 
Not leave me this way.
You could have told me 
Not waited for so long.

       G                          F
For so long I never realised just exactly who you are.
       G                         F
For so long I never realised the girl I had before.
       G                                      F
For so long I hope you're satisfied you won't hear from me again.
       G                                           F
For so long I hope you're pleased with what you've done.

Chorus
Why didn't you tell me. 
Not leave me this way.
You should have told me 
Not waited for so long.

F G C  to finish

Riff played during the Chorus
E-|-----------------------------------|
B-|-----------------------------------|
G-|-----------------------------------|
D-|------------2----------------------|
A-|----3---3-5---5-3-2-0--------------|
E-|----------------------3-5----------|