RioIndy:
Let me offer a slightly different perspective on your situation. It may seem like the long way round, but bear with me.
When I was a young boy in Sunday school, I memorized the prayer found at Matthew 6:9-13 ("Our Father . . ."). It didn't mean much to me at the time. It was just something that we said at the same point in the Sunday service every week, although there was some confusion when we changed churches and had to say "forgive us our trespasses" instead of "debts." It was not until later that I read the verse which follows it -- "if you do not forgive others, your Father will not forgive you." At first, it just seemed a fair exchange - forgiveness for forgiveness. You know, the whole "do unto others" thing. But then I got to asking myself "if God forgives those others, why do they need me to forgive them?" That proved a question for a later day.
It was not until I had many more years under my belt that I began to understand the point of the biblical injunction -- forgiveness is not for the benefit of others, but for me. When I hold a grudge, the anger and hatred that I carry around in my heart controls me. It affects what I think, how I feel and whether I enjoy my life. It even affects me physiologically; I have trouble sleeping and my blood pressure rises. I am quite literally in thrall to those whom I hate. It is only by letting go of my anger and sense of grievance, by "forgiving," that I can wrest control of my life from the grip of those who have harmed me.
It seems to me that this is also the whole point of becoming financially independent and retiring early. We want to regain control of our own lives, to live in freedom and independence, answering to no one but ourselves. That means not just physical freedom, but mental freedom as well. To that end, I think you should pass on the opportunity to "speak your mind" on the way out the door. As much as your supervisor may deserve a tongue-lashing, it is crucial to your future happiness that you just let it go. It is something that happened long ago, in another country, and it should not occupy a single nanosecond of your thought after you are gone. I fear that if you indulge your current grievance, it will.
Gumby