Hairy,
Have you ever asked her why it's YOUR job to make HER feel "safe"?

She has anxiety where sex is concerned. You are sympathetic and willing to help her through this. As far as I'm concerned, that's where it has to end. You cannot contort yourself into a pretzel in the hopes that she will finally, at last, feel safe.

She doesn't even know wtf her own definition of safe is.

I would tell her that unless she can define it, in measurable terms, that you are unwilling for it to be your yardstick any longer.
"I'll know it when I see it" has GOT TO GO!!!!!!!!!!!!!!!

P.S. Good for you for how you handled the convo. You rock, man!