Found it!

DEAR JOHN
#1 country hit for Jean Shepard and Ferlin Husky in 1953
-Words and Music by Billy Barton, Fuzzy Owen, and Lewis A. Talley

CHORUS
Dear John (Dear John)
Oh, how I hate to write
Dear John (Dear John)
I must let you know tonight
That my love for you has gone
There's no reason to go on
For tonight I wed another, dear John

SPOKEN: I was overseas in battle when the postman came to me
And he handed me a letter -
Aww, I was happy as I could be
You see, the fighting was all over and the battles, they'd all been won,
Then I opened up the letter and it started "Dear John."

Dear John (Dear John)
Oh, how I hate to write
Dear John (Dear John)
I must let you know tonight
That my love for you has gone
There's no reason to go on
For tonight I wed another, dear John

SPOKEN: Will you please send back my picture?
You see, my husband wants it now.
When I tell you who I'm wedding you won't care, dear, anyhow.
Now the ceremony has started and I'll wed your brother Don.
Please wish us happiness forever, dear John.

Cheers
JennieG