Since a couple of others are commenting about things other than the ending, here's what I was going to say...

Originally posted by Lost:
V-1
How do you teach a heart to say goodbye.
What do you tell a heart that ask you why.
Well darling if you know
I wish you’d tell me so
“Cause my heart's about to break And Then I’ll Cry


"And then I'll cry" sounds awkward to me. I love your verse up till then. A lot.

Chorus
One final kiss goodbye
And Then I’ll cry
If forever just can’t be.
and I have to set you free
My broken heart will think it’s goin' to die


And my other comment was going to be to change the rhyme from the "i" rhyme that you used in your verse.

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My sig: Good luck, songwriter! (OPINIONS: Producer regarding The Beatles... "Guitar music is out of style; I'll pass." George Jones: "Yeah, I've recorded a tune called 'He Stopped Loving Her Today' but it's too sad; it won't go anywhere.) And you want MY opinion?