My sister tried the same things with me, even having my 4 year old niece ( at the time) relay the Jehovahs is going to kill you message. When I wouldn't engage she became even more enraged and tried other more bizarre threats. Now she leaves me alone because I won't enagage.
She has sent notes to her DF'd son about how Jehovah is going to kill his baby if he doesn't return. Ummm yeah makes me want to run back. Plus isn't it supposed to be Jehovah who judges people's "hearts" not our sisters? Sorry your family is crazy too :-)
edit: Once they can't scare you anymore they have got nothing left to compel you to return.