That book was written by a human several hundred years after Christ and based on a person's interpretation (and it would be unreasonable to assume that none of that person's own beliefs or bias got in there whether they meant to or not).
If God exists and I ever meet him, I'll ask him what his views are. That's just my opinion though.
I'm starting to feel sorry for her fiance as well. Sorry I don't have any advice other than to stick up for yourself, but that's a conclusion you're probably going to have to come to on your own.
Out of curiosity, how old are you? Aka how long will it be until you can move out?