Heather, You can write a note, but then either tear it up on place it somewhere safe. Your h isn't ready to hear or read what you have to say.
Love Must Be Tough doesn't work well w/the mlcer because you are dealing with an emotionally hurt person. It's good to read this book and see what types of tools Dobson offers, but it's not one of the "tools" that I would suggest to use for someone in deep mlc.
Heather, there will come a time when you can give your letter to your h, but it's not going to be for a while. Replay scrambles their brains and they really couldn't give a fig how we feel right now.
Please take care of yourself.
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.