Here's the odd part for me.
You've never had sex with anyone else and never thought of it, wanted it, or would allow her to do it...yet, your first sentence is that you have been lurking here (on a swinging website) for a long time, and she only brought this up just the other day.
Why the lurking??
It seems you have had thoughts of something. I don't research how to build rockets, cuz I just have no interest.
You can help yourself discover the answers to your own questions by being honest with yourself first.