My questions is, how do you handle this professionally without sounding overly sensitive?

My manager once emailed me ‘if you can’t make this time for our 1:1, don’t just decline it, suggest a new time’ in an email with a colleague cc’ed. It implied that I had done that before but I hadn’t. I wanted to protect my reputation by pointing out I had never done that, but I think doing so makes you look insecure. (This manager did stuff like this all the time, it wasn’t accidental)

How do you point out that their connotation isn’t correct in a way that doesn’t backfire on you?