I think that you are walking on eggshells, expecting not to break any.
As long as there is not conflict, your husband is in control. Since he is in control, why not query him for his plan. Surely, he has one, since he is in control.
I think the letter will highlight a hole in his own space.
So my answer is a question. Can you handle the fallout from a direct question of hubby or not?
If hubby had a track record of being a good leader in the marriage, then you probably wouldn't mind tagging along without serious reservation.
In real life, your hubby has led you in circles. I think you should know what his plans are before you blindly follow along. I think you should know if he has any intention of working on the relationship, and "give it a month" is not an acceptable answer.
You don't have to push to find out what you need to know. You don't have to threaten, just ask a simple question. No answer is still an answer.
You can't live in fear of the answer. It really will determine how you live the next 10 months of your life.
-NOPkins-
I will ferret out an affair at any opportunity.
-An affair is the embodiment of entitlement, fueled by resentment and lack of respect. -An infidel will remain unreachable so long as their sense of entitlement exceeds their ability to reason.