XXXs,
Well the letter may never arrive. At this moment you are future tripping over a letter not in your possession. This does give you time to leave it in your HP's pocket.
That sounds good above, but honestly I'd be totally future tripping too.
The letter basically has 3 possible messages:
honest amends worth reading for your own recovery
an honest amends that you should not read
an attempt to pull you back into the addict's world.
IF you receive this letter, you could decide to entrust it to someone helping you in your recovery. That way you would not be tempted to open it and could deal with it when you feel more at peace about it. Personally curiousity would get me and I would open it even if I knew it could hurt me. One approach could be to ask this person to read the letter on your behalf. Let them determine the nature of the letter. If it is a worthwhile amends, entrusted person asks you if you want to a) read the letter, b) further delay until you are ready or c) burn the letter but know it was positive in its nature. If it is not worthwhile, it is burnt by entrusted person and the amends is given over to the universe.
I am so glad to hear you are doing well. We so want to help the A that even now you probably want to do the 'right' thing. My first therapist told me she liked working with Codies because we were such nice people. Peace in your HEART and resolve to let your HP guide you in the right response IF you have to deal with this letter.