I reviewed the thread before commenting, and yeah, neither of you is really making any progress with the other. Up until this point, however stubborn either of you have been, neither of you has been overtly snarky or condescending.

As for a "burning desire to have the last word", I see no less desire on your part than on theirs.

Oh I see your problem. Your perception is way off. Please allow me to correct your misunderstanding once again and hopefully for the last time.

This goes well past the line of civil discourse. Communication is a two-way street, and requires active participation of both parties. Once you decide that it's all their fault, rejecting the possibility that you're not communicating your ideas effectively, you're no longer participating in good faith. At this point it's better just to back off. (As I'm about to do.)