I'm white and have spent most of my 70 years in the deep south. Yes, we are known for our high-profile racists, who range from murderous supremacists to fun-loving Confederate flag waving good ole boys. But we have a sizable layer of polite racists not unlike the comfortably closeted racists you describe in your region. These polite racists depend on the yee-haw racists in order to establish their innocence.
As you point out, racism is the original sin of America. It permeates our Constitution, our statutes, our hymnals. It is possible to defeat sin, but the first step (according to most theological traditions) is to feel contrition. And the second step is to work actively and tirelessly to combat sin by doing good things instead of evil. Only those who want to exult in their guilt will proclaim their innocence.
I would imagine that your heartfelt examination was not easy to write. But it's clear from the comments here that you've moved many of us out of our comfort zone and onto the path toward compassion and justice, which is the only path we should follow. Thank you for your clarity and your courage.