I agree with the first response in that you should keep from talking to your fiance about it right now. He needs to keep his mind focused on what he's doing right now. I wish I could give you some advice but I don't really know what to say other than I'm sorry you are in this situation. I can relate in a way; several years ago I was dating a guy, one drunken weekend he had with all his buddies, one of his friends slipped out to me that my *ex* boyfriend had hanged the family dog in their backyard. Words can't describe what I felt in that moment. In my situation, there was no way I could be with someone like that, he didn't have any other animals so there was nothing more for me to do than just leave.
Maybe your future MIL needs some help with alcohol abuse? Not trying to judge here, but if she is doing these things when she is drunk
