WB, I think your letter is emotive and beautiful. I would think that sending it would be a good thing. However, I would also be prepared for the worst. If H is confused, who knows what is going on in his brain and how he will react. I say this from experience as early on in the piece I sent my H a letter, carefully vetted that he took totally the wrong way. Even though there was nothing negative in it.
I know that you are further down the journey and your situation is different, but felt it should be mentioned so that you are prepared. I guess this is a case of " expect the worst ~ hope for the best".
I guess there comes a point in this journey that we really think "enough is enough" and if you are at that point (crossroads really) then you really need to know. In your case, it has real implications for you and your family.
The content of the letter though is full of love and caring and respect and personally I cannot fault it.
Good luck with your decision. I know you have the strength to do what's right for you. Mind you my stars say with the eminent eclipse, now is the time to make wishes, especially on the r front. Here's the link if you are interested Yasmin Boland's stars Good luck