A.M.
I have no experience with this, but if I were in your shoes, I'd show him the letter and just take it from there. By doing that, you aren't accusing him of anything, you're just being honest. I suspect his reaction will tell whether or not there is any merit to the letter. It is always possible the person who sent the letter perceived wrongly... Or she's a crazy person... I'd be unnerved to receive a letter like that, but I'd show it to my hubby before I let my thoughts run rampant. I'd also pray about it bigtime before showing him the letter--as in, Lord, please give me the right words to say and let us be able to discuss this openly, honestly, calmly, and with love and respect for each other. I'd say something like this when showing it to him, "I got something kinda bizarre in the mail and in the interest of full disclosure, I thought you should see it.".