You asked about resources - I usually recommend Franklin's articles on Polyamory at http://www.xeromag.com/fvpoly.html
, especially the front page that goes through a lot of the common questions that are asked in situations like this.
I, too, have had some pretty rough "coming-out" discussions with friends, some that caused a large distance to be put in place because they didn't want to have to deal with it for whatever reason (which I suppose it their right). I can only imagine how much harder it must be for a family member. I feel for you.