To accept it, you just move on with your life. Find the next thing you should do and do it. The more you dwell, the harder it will be to stop dwelling, so just break the cycle and go do anything else.
You will encounter plenty more people who are insistently wrong. Each one will affect you less than the last.
So these people who were rich enough to own a second home wanted to spend more than 50% of their time in France, but were paying the vast majority of their taxes back to the UK?
No wonder the laws got tightened.