One question: any chance she would EVER learn about it?

If no, it's between you and your god.
If yes, it may between all three of you.

If I was in your shoes and I knew she was my everything forever, I would probably live with it, and one day - maybe 10 years time - if you are still together, find a way to hint that for one day one other person caught your eye and that was it... Best of luck. All anyone wants is peace and happiness, inside and out.