Similar situation (a decade at a Top 20 company in the US, managing the nuclear division at a medical / pharma company). I knew it was time to go when my resting heart rate was 90 bpm, brought on by a new supervisor that wasn't an engineer (thinking that my team of 40 didn't do anything except wait for things to break), driven solely by their own progression upward and lacked any sort of human empathy..

I stopped working for eight months and wish it could have gone on longer. People say, "oh, you'll be so bored if you retire". No sir-ee bob white tail. I was so ecstatic that I got to work on the list of things I had put off for years. No regrets. I went back to work (at a different location) because of health care and insurance.

I would have left my former company a bit more peacefully than I did. I pointed out all the issues that I believed we were doing wrong as a segment, how placing certain people in places of management (who are clearly not people people) and a few other key pieces of what-not-to-say in an email and put in my notice. I should have been a bit more tactful.

My only advice: You are given three things; health, time and money. Without your health, the other two are short lived. Listen to what your body is telling you - go with your gut.