Fabulous! I love how he said that it wasn't just the witnesses. I think that takes a little of the personal attack (in her mind) out of it - not much, but a little. I also love the way he turned the evidence of the truth of the Bible around on her. Did he do that letter all by himself? I am amazed at his critical thinking and his huevos!!! You have a son that can think for himself and you should be very proud!
I do have to say, having a brain washed fanatical mother myself, I was surprised at her letter. From my eyes, I thought she really was kind and loving. It was gentler than I would have expected. I am sure she is very saddened and in shocked. I know my mom was beside herself when a few of us kids came out.... the letters may get stronger and stronger, at least my mom's calls and letters became "desperate" and the guilt trip intensified which only made me walk further away from her. They just don't understand that their tactics on the "wavering" are counter-productive.
I also I think the part that is upsetting you is the unhappy 19 year marriage part!!! ROFL!!!! (just joking! - sorta)
Gringa