I totally hear you!
I have been told:
"You were so cruel to me once when I cried, you told me I looked unattractive crying". I SO DID NOT DO THIS! EVER!
I also was told by a friend of hers "I said to X, the first time you called it off... . " <--- I never, ever called off our relationship! I asked to put the wedding back a year, that was all.
I was also accused of practically sitting on my ex-gfs knee in a nightclub - ermmm? Why would I do that with her there, and HER gf's cousin was there too! I was simply sitting next to her, talking into her ear as the music was loud.
The false accusations hurt, I know. It's like, why did I bother being so lovely and so supportive, when it all gets twisted anyway?
I think your message was excellent -nice and detached, made her feel like she was being heard, and didn't get into it. Well done you

I shall have to try something similar!