First off, as others have said, let her bishop know what's been happening if you haven't already. It needs to be dealt with before your gf's situation gets worse and before similar things happen to others. His calling is to deal with this kind of thing, and he will receive revelation on how to do it. As for how to resolve things between you and her, I would make it a matter of prayer and/or fasting. You can receive revelation on how the Lord wants you to handle things. Maybe you take a stand and risk offending her for her own spiritual safety. Maybe you let her pray and decide for herself. Maybe you end things now, or possibly you ask the bishop or your family for advice, or something totally different from any of that. I really don't know, but God does, and He will help you make things right in His own way and time. Best of luck.