Is he aware that if your children are faithful members of the church they might end of marrying in the temple and he would not be allowed to attend the ceremony. They want a man who has navigated the stormy seas of the world, who has just a little bit of history, and has overcome the degenerate worldly culture, a man who has discovered for himself where peace and happiness lie. Her brain has been wired from birth by said cult. I feel to say, if you hear this, Amy, in time, it will all come round right. I recently left my family, friends and state to move across the country to be with my best friend and boyfriend during his residency.
You've made good points about not bringing up the CES letter or anything that could be called "anti-mormon. They believe that the body is a temple that needs to be worshiped, and that inner beauty is more important. I am a non Mormon. You can't reason with fanatics, and you got one.
Invest in your love and keep it strong. This also means giving her something specific to do. Basically nothing like reality. You just can't imagine the heap o' hurt you're potentially setting yourself up for. But I loved this girl more than anything in life. Have you seen southpark episode on Mormons. Why would you behave any different now.
Make an honest effort, and see if you reach the walk-away point. All of which will remind her that she wants you to convert so you can be together for eternity. To me, the core question is, is this person inclined toward self transcendence are the inclined, desirous, self aware enough to be selfless. This can be a good way to learn more about your personalities. Good luck to you and your boyfriend. This can be a good way to learn more about your personalities. If you can genuinely deconvert her then cool.