But how do I handle this?
First, big hug. It's quite A story and that's the least that we all can give you.
I don't know the specifics about your relationship with other JWs or any other attachment that you may have, even if you decided to stop going. I say this simply because it's impossible for me to completely erase my first 23 years of life born-in and raised a JW, leave alone 60 years.
I'm also inquiring because I could tell you what I would do, which is not advise, nor is it something I necessarily encourage you to follow.
What I would do is that every single time that every single JW contacted me, I would not drop the topic of the abuse and the letter, and talking to the elders, and them turning their backs on you. I wouldn't miss the slightest opportunity to give them a reminder.
To me, doing that: (a) would give me the power to let them know what needs to be addressed if they want to deal with me at all, (b) will force them to either address the issue or leave you alone once and for all.
Again, this is what I would do. Another course of action is just letting them go. Be always busy, always "will call them back", always have something to do and never have all the time in the world for them. remember, you are no longer supposed to be obligated (you never were, anyway) to drop everything and talk to them just because they say so.
One more thing is that you have a great asset, which is your non-JW family, and a husband who knows where you are coming from. Use them, get closer to them, get their support. I'm sure that they will be on your side.
When it comes to sexual abuse, the trauma is not just the event; it's also that disgusting coverup that people do. Sadly, religious organizations (many, though not all), are as guilty of doing that very same harmful thing.
I hope this helps, and another hug.