Lol, your aunt doesn't quit, does she? Descartes pointed out two very important things about logic, the first being that logic is solely about form, and not content. Secondly, the vast majority of flaws in reasoning are not formal, or flaws of form, but of content. So, I'm saying that your aunt is simply ignorant, and reasoning with her won't do anything, because she sounds like someone that trusts her reasoning a great deal, and her reasoning is probably most times valid -- but that doesn't make it sound.
In Ayaan Hirsi Ali's book, infidel, she recounts a time when she told her mother about the moon landing, to which she replied something like "stupid Americans, go up to a high mountain and think it's the moon", just because she didn't know anything about it, and reasoned about what was achievable, based on what she thought was possible.
It isn't your job to educate your family, but you would do well to educate yourself, which will give you more confidence in the soundness of your position, and this confidence will radiate from you, and make others feel less confident about the truth of their own convictions.
