Thanks for the replies, everyone.
My sister is still happily married to the same man. Their daughter has recently graduated from college.
Almost 30 years later and she is as happy as can be despite the JW making claims that she returned to the vomit and the world has nothing to offer.
The other thing I want to respond to is about the relationship being irreparable. I'll never get those 17 years back. I never got to spend time with my niece. The stain of the Watchtower never goes away. Sure, it fades away little by little but never truly totally.