How do I prevent Siri from reading and sending messages via AirPods during sensitive conversations?

My iPad was locked but nearby. My iPhone was in another room. My Apple Watch was off my wrist and being charged. I had one AirPod second generation in my ear. I was having a sensitive conversation with a health care person when Siri started reading an incoming message from a company trying to sell me something. I touched the AirPod to shut Siri up and it started taking dictation and sent an SMS message of part of the conversation to the company trying to sell me their product. To add insult to injury, my cellphone plan charges me a fee each day I use the phone so I got a charge for this message that should never have been sent. How di I turn this behavior off? I don’t want Siri reading incoming messages to me.

[Re-Titled by Moderator]