This is utterly horrific and despicable, Lee. Terrible not only for the personal embarrassment it could have caused you, but for the potential professional impact. I urge you (via the police) to pursue this matter as strongly as possible, so that the culprit is identified and brought to whatever justice is possible.
As for leaving the BCG, I understand your reasons, but I would urge you to at least take some time to reconsider. I would simply say that if someone is out to maliciously target another person (for whatever warped reasons) then their absence from a forum such as this is unlikely to deter them. On a personal note, of course, it would be such a shame not to have your cheery presence around. (I hope at least you will stay on Facebook in order for some of us to keep in touch with you and your career.)
Also, thank you for bringing this to everyone's attention. Without trying to sound selfish, I imagine that this has sent shivers down some of our spines. Especially those of us who are trying to forge a career in writing professionally. If anyone has any knowledge of the culprit, or has experienced similar, then I would urge them to PM Lee, or alert the rest of us in some way. The waiting game for feedback as a writer is bad enough without the fear that anyone might be maliciously trying to derail one's career. You don't need to add this kind of thing to the list of reasons the phone might not be ringing.
All the best, Lee, mate.