Hi RDW,
You have my sympathy for both your loss and your situation.
My Mother-in-law was in the same boat as yourself a few years. She had been ousted by the JW's many years ago and her life was made a misery by her parents who were still very active within the org. They would pop in and out of her life when it suited them, cutting her off from the family when their other JW children questioned what they were doing associating themselves with her. She had her heart broken more times than I can remember.
When her parents died (seperately), she made the decision to attend both services at the KH, and all her children and myself went with her for much needed morale support. We made sure that certain individuals weren't able to get near her, and sat quietly at the back of the KH in our own little group. It was about paying respects and saying goodbye, more than anything else, and it did seem to help Mum. I don't think she'd have ever forgiven them for their short-comings and hurtful behaviour, or herself if she hadn't gone. She's been able to put the past behind her and move on with her life, without any interference from her JW siblings.
Saying goodbye is very important. Human beings need closure, and just to attend the service without actually taking part in prayer or singing will help more than you'll know. You only get one chance. If you decide to go, take close family or friends with you for support and protection from unwanted attention.