Turkey,
Personally, I would do it in a letter. I myself have drifted away so as not to cause any bad riffs between me and my parents or bring disgrace on the family name. Part of me would LOVE to DA myself, but my parents are well along in years and in poor health. If I were to DA myself, I would have to sever my ties with them and they won't live forever, no matter what they may think. So, I choose not to at this point in time.
If this is not an issue with you, I would do it in a nice letter, explain why as well - your last chance to get in the last word. Note also that you will not accept being called on, talked to or bothered EVER by another JW unless you initiate contact first. You can have the letter notarized and sent via certified mail, UPS or FedEx. This is what I would do and my advice to you. Hope this has helped.
Kind Regards and Hugs,
Moe
UADNA - FL
Unseen Apostate Directorate of North America - Florida Division