I think standing your ground is a fine idea. But leave off the bit about having asked others because she'll a) start on about who you've been speaking with. And b) it lessens your show of personal strength.
Just put it forward that this is who you are and what you believe and it's not up for negotiation. Each time she raises the topic in future, remind her that she knows how you feel and that you will not be discussing it with her.
I do believe she'll probably leave you over it and go find someone else who will pay her bills - but you will at least know that this will be an informed choice by her.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.