I'm sorry you took offense at our humor. MAybe we were a little tough on you.
But you say this is exactly the reaction you are fearing at home. And will you also quit when/if your W reacts the way we did? I hope not. I hope you two can duke it out. Because the way I see it, her reading your letter, reacting badly and you reacting to her reaction etc is the salvation in all this. Working THROUGH that, not avoiding it or quitting, is the only way to save the marriage.
I can understand that it will be incredibly hard to do this if her response hurts your feelings, but it seems to me that this dynamic is where the problem lies.