I am glad your sister responded to your text. I hate to see any family torn apart by this hateful cult, anything we can do to combat that is good.
I think there are a few reasons a health trauma hits JWs harder than others. For one, it reminds them that they may very well die in this system, something they didn't think would happen. It also sidelines them, at least for a while, from theocratic activities. They may then find themselves being judged by others for slacking off, or at the least realize that they are quickly forgotten by the congregation. This is a religion that shoots their wounded, which can be a painful realization.