My dear Isabel C. I do love grammar so.
Evidently, you fancy yourself as a bit of a grammarian.
I do not believe that I have committed a grammatical faux pas as the French might say.
If I have violated a grammatical tense or mood, then enlighten me of my transgression.
It wasn’t a grammar mistake. It was a mistake in logic in which what you are saying is the exact opposite of what you think you are saying.
It’s a common mistake, especially among those with little experience reading English. Just read more and you’ll be ok.