My heart sincerely goes out to you. I too know what it is like to experience unimaginable pain when dealing with immediate family members who remain Jehovah's Witnesses. I know we did not exactly get off on the right foot, so perhaps a little background would better explain my circumstance and how we are very similar.
My mother remains a Jehovah's Witness. She was BORN into it over 55 years ago. You see, I am a 3rd generation JW, and am the ONLY member of my family to exit. Because of love of my mother, I once tried to show her a plethora of documents (even taking direct quotation from Watchtower bound volumes, which I have a library from 1945-present) to expose her to the reality that the Jehovah's Witness religion is a lie. I love my mother, and was doing this out of concern and desire to not see her live the rest of her life dedicated to a lie. I was told to my face that I was a disappointment as a son, that she had failed as a mother, and that she could not love someone who turned their back on Jehovah God in any such fashion. I have a brother with two children of his own, and I do not see them because they remain loyal Witnesses, and pretty much want absolutely nothing to do with me.
My advice to you is to be prepared for heartache and frustration. No matter how hard you try, you cannot make an individual change their beliefs. In fact, the harder you attempt to show them facts, the more they will reject you (it reinforces the indoctrinated notion that you are an Apostate) A person has to be capable of thinking for themselves (not insinuating that your mother is not able to, but that she prefers to cling to Watchtower sanctioned literature and organization-provided thought) and realizing that blatant and glaring issues are completely wrong within the WT organization. Until they are willing to discuss things rationally, you are just slamming your head uselessly against a brick wall.
My sincerest thoughts go out to you, and I hope things get better. Believe me, I DO know your pain.