What a sad situation. My husband's aunt is in the process of divorcing her controlling husband. They aren't JWs, so they don't have the issue.
If he is harassing her, then she needs to see about getting a restraining order. I would also suggest she seek counseling from a professional. A good therapist can help her to find her own source of inner strength and to stay strong.
Personally, I think that her husband broke his vows first. By trying to control her and harass her he is not loving, respecting, or cherishing her. He seems to be missing all the advice the Bible gives to men about marriage. He has broken his vows and she has a right to end the marriage because of that.
The best that you can do is to be there for her. Hug her when she cries, hold her hand when she makes hard decsions, gently encourage her to get whatever help she needs from the pros, listen to her, and remind her of God's love for her.
I hope this helps. I hate to see anyone in this situation. I really hope she will seek help from a good therapist and a good lawyer.
AmazingProgeny