Write the letter, but then burn it and/or tear it up. Your h will not receive it in the way that you intended. It will make him feel guilty and shame for what he's doing and yes, may even make him a tad angry. He will look at it as a last ditch effort on your part to sway him to your side.
I know you would like to reach out to him and tell him your thoughts, but now is not the time. Sit quietly and the answers will come.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
