Not him as an "ex", no. Here's my take. When its over, its over. Period. Doesn't matter how it ended. It just is, and I refuse (and am too proud) to continue any communication.
You have the option of burning the letter, or shredding it, or something symbolic instead of sending it. I agree with you in the sense that I would be afraid of a response AND afraid of not getting one too. Is it really worth that?