I agree with Searcher and phizzy. You don't need to tell her about what you may or may not be reading. I would also be sure to stress your love for her and that you will always be there for her no matter what. There was a point years ago when my parents informed me that they could no longer come to my home for dinners and have contact with me for anything other than strict family business and my response was that I understood and that I loved them and that I would just be a phone call away if they ever needed me. Within days they retracted what they had said and I am happy that we spent may good times together. My mom is gone a year now but I am still and will continue to be here for my dad.
One thing I told my parents when all this was happening was that I was much too young to make a decision to be babtized and there were just things that I couldn't understand about condemning other people who so believed so deeply in their hearts that they were worshipping in the correct manner. Just exactly how the witnesses feel. So just like they could not be convinced otherwise how could it be fair to destroy someone else who held to their convictions so strongly.
Please do not destroy this relationship (however limited) by trying to comvince her that her beliefs are wrong. I wish the best outcome for you.