Yours is a uniquely difficult situation, and I can't presume to tell you best how to proceed. Others here are older than I am, can better relate to your particular situation.
What I did want to say is this: after a year of worrying about other family members and whether they will or will not turn me in if I do or do not toe the line, I've finally developed a "do-whatever-the-hell-you-want" attitude when threatened as you have been. I hope that in time, with the help of those who can listen and relate, you'll feel something of the same confidence.
Meanwhile -- there may be some deceit or subterfuge by which you can avert all this; however, I sense that you have too much integrity to compromise your stance. So, my advice is simply to say as little as possible when discussing this with Witnesses. Avoid explaining or dissecting your feelings and opinions ... and be prepared for elders to try to get you to say that the Organization isn't being directed by Jehover Gawd. The less you volunteer, the shorter your answers, the less likely they'll get the confession they want.
Finally, your experience reminded me of one I had in high school, though it was less serious: in class one day I called another student an "asshole" (he was) in front of another Witness. The Witness told me to tell the elders about my "worldly behavior" or else she would. So I told an elder, only I played it down, a lot. Said I'd lost my temper (I had), used language I usually didn't use (true), and wished I'd thought of a better way to handle things (also true). Threw in a bit about how I'd prayed for more self-control (true if you equate "wished" with "prayed," which I sort of do).
Your situation, of course, is a thousand times more severe. But maybe there's a way to tell the elders without being dishonest and at the same time deflating the whole situation. Pull aside the most easygoing elder in your hall (if there are any), vaguely mention the e-mail that has somehow (insidiously) found its way to your mailbox, etc. Have an easy demeanor, and maybe you can laugh it off as part of the quirkiness of the internet or even Satan's expanding repertoire of dubious snares for Witnesses ... then go back to your son, say you've discussed the matter with so-and-so, and the details from there are confidential.
I don't know if any of this helps, and like I said, I'm probably too young to appreciate your circumstances precisely. I don't know I've gotten a lot from your posts these last few days, and hope you'll stick around.
Dedalus
