The first thing that Bible Students are taught is that "well meaning but misguided friends and relatives will no doubt try to get you to stop studying ". The more you oppose , the more true the Witness teaching seems to be. I would commend her, be pleased for her , that she has found a faith that fulfills her needs.
But , just as you would not by a car without an independant inspection, urge her, challenge her if need be to at least look at a couple of independant websites . I would recommend Freeminds.org and JWFacts.com.
She has to come to a conclusion by herself......good luck
^^^^This.
She is needing something otherwise her radar and alarm signals would be going off. Try to find out what need the JW's are filling. Question things she is learning from a curious "that makes no sense" standpoint.
As was said ...she is lucky to have a friend like you. Try to save her if you can. Good luck.