Ucant,
I sympathise. I devoted years to what I saw as The Truth. I still believe that many Witnesses are christians. I dont' see current teaching and practice as christian. But I have regrets. I regret things I said because I now see them as wrong. I spent some months trying to redirect an abusive elder, and ended up being abusive myself. I am, alas, now a cranky old man.
But new life is new life. If you are certain the Witnesses are wrong, then don't look back. If you regret what you've done in the past, make is as right as you can and leave the rest in God's hands. If you feel you need to return to revalidate where you are, attend meetings for a while. See if you feel other than you once did.
I think the Watchtower is wrong in vital areas. I do not see them (most of them anyway) as anything but true believers, even if they are misguided. I'm not a uinversal salvationist, but I think the book of Jonah teaches that salvation comes even to those who are misguided and child-like. If Witnesses are that, they are still within God's Grace. I know not many here think similarly. But that is how I think.