Hi Len, thanks for sharing your story so far. I too read the whole document.
First of all I'll start by saying I don't think you deserved that thumbs down on the OP - it takes courage to divulge personal parts of your life no matter how much others may disagree. So you get props from me for that.
I hope you don't mind a bit of frankness from myself though? It's easier for me since I've never met you, and I'm looking at something with fresh eyes. Hopefully this isn't received as something downright rude...
I would not have gone into the exact reasoning's as to why you left the WT org, especially as this just comes across as bashing their faith (or "whining") - hence the reason for the quick scan by one son. The minute they reached the "negative" (to them) parts, they would have switched off. It's only natural. It's enough to say you have your differences, and have come to your own conclusions.
What a child is most looking for in a father is simply recognition, for them to perceive that the father is interested in THEM (not a concept, not a subject, not a thing, not a religion, not intellectual debate, not excuses, but **themselves**). A letter like this should be personal, talking about feelings etc as apposed to "facts". You, being an engineer would likely see things in an extremely rational/objective manner. It's a blessing and a curse. So to you, explaining the exact ins and outs of why (i.e. your problem solving nature) seems like the most logical thing to do. Unfortunately the average person does not think like that! Especially not children towards the parents. Emotions are higher on the scale than black and white thought. A parent doesn't have to be perfect, they can make up for a heap of shortcomings just by coming across as exclusively interested in the child (despite any differences in personality/values/belief). The 1 to 1 attention comes first, "things" (all the baggage) etc are secondary.
This letter began well but went wrong when it veered off on a tirade about the WT and very little about your simple desire for a relationship (which at the end of the day we all want, when you strip away the religion etc). You've had 3+ decades away from your children with zero contact, then out of the blue they receive a letter from their father with hardly any substance in it other than what appears to be (to a JW) cut and paste "apostate material"! No offence but this is exactly how a JW thinks. Oh the irony. We leave WT often to just rehash the same inappropriate social skills, just in another ex JW way. So, say for example a JW funeral is all geared towards making more converts (or getting strays to come back) instead of talking about the **person** (something we ex JWs cringe at), an ex JW too can fall into the trap of only ever talking about the woes of the JW religion instead of just showing an interest in the **person**.
Sadly we ex JWs can carry the same retarded baggage that holds JWs back (i.e. being trapped in their own mind), not realizing that we're often the instigators of our own pain. A simple analysis of cause and effect shows that to speak negatively of a person's cherished beliefs will push them away, no matter how "honest" and "steadfast" we believe we must be. We then bemoan that "this terrible cult has taken our family away", entirely neglecting to put ourselves in the same shoes we once wore.
This probably sounds harsh, but hopefully it's helpful in some way when talking about ex JW to JW communications.