Do the situations ever get resolved if you don’t send the letters, or do you use the letters as a basis for having a more mature conversation after?

I sometimes do the same thing, and after I get my ideas out/vented, I end up rewriting the letter with gained empathy/understanding, and then use that as an outline for a conversation (if not reading the letter verbatim for especially difficult subjects) with the person. Otherwise, even if I feel a little better, nothing actually was resolved.