Hi dlish. Sounds like you have some type of synaesthesia.
I like the analogy, "spelling is to writing as arithmetic is to mathematics". I may use that.
Ultimately, in professional writing (such as work emails) I am more irritated by someone who proof reads poorly and sends something that is not what they meant than I am by use of "American" vs. "English" spelling - in my trade I see a lot of both, and start to ignore it (although clearly English spelling is correct, and American spelling is wrong).