You have a HUGE battle on your hands and ultimately the decision lies with this lady you are with at the moment.
I can only sympathize from afar.
She will have the idea in her head that Satan is working through you to move her away from the truth. As you probably know!
Many others have gone through what you are going through at the moment and have come out the other side.
I think practically speaking she needs to examine her religion and see if it stands up under scrutiny, try "In Search Of Christian Freedom" and take it from there.
I would advise you not to pressure her too much, but allow her room to breath.