well, junebug, you are smart,,you are an investigative, researcher person. The Watchtower organization will want you to stop that. They will want you to only read 'their' literature. They want to do your thinking for you. You would be taught to be submissive to your husband, and also to the Governing Body (7 guys presently, all totally supported comfortably by donations by mostly not rich Jehovah's Witnesses). Suggestion: when the JWs say "the truth," interject at least in your own mind, "the program," because it is in fact a man-made high-mind control program that will use you all your life.
You sound like you have a healthy, strong respect of your parents. The JW organization will want to break that down and encourage you not to see them very much, unless they too become JWs.
Your boy will be burdened by them. That is why many (66%) young JW men & girls leave, throw up their arms in exasperation at the unrealistic demands put on them. They must go to school and have no non-JW friends, no flag salute, no national or holiday songs nor arts, taught explictly the evils of masturbation, no sports, no dating except for marriage (forcing many to marry way too young). Let your boy be just a normal boy to enjoy his childhood. The JW world just wants the youth to almost skip that childhood phase. The childhood goes by quickly.
I was a 9 yr old girl when my folks became JWs. I was taught the new world was, just around the corner, so soon,, 55 yrs ago. There were reasons why your fiance walked away from it, but he has forgotten the reality. Maybe he got understandably spooked with your son being so critically sick and JWs and inactive JWs can be superstitious when that happens and then they let the "guilt" get to them and then they reactivate and/or maybe he is liking the idea of a "submissive" wife potentially.
I love it to see people like you coming here and checking many sources as they learn the "whole" story through and through about JWs.