Someone who I thought was a friend reacted badly to an overly frank account of my life with my new slave-wife, and among other things passed it on to my sister for comments. (Even when I made it up with my friend, I never got clear why she did that.) My sister was... concerned; if she was shocked she tried to put it to one side, but she wanted to understand why she shouldn't conclude that I or my wife or both of us were seriously sick puppies. (I think the worst case she envisaged was that I was some kind of monster abusing someone too emotionally sick to resist.) We exchanged some very intense letters, at the end of which she allowed that while it looked very weird to her she accepted that it wasn't harming either of us, and beyond that it wasn't her business to judge.

In a way it helped that she and I had never been very close, so it wasn't too hard to get back to where we'd been. She's always treated me with what looks like exasperated tolerance, so this just gave her another reason to see me as only barely legally responsible :-}

I'm afraid this might not help you, because that solution depends on having someone who really wants to understand and make the effort to see a very alien point of view. It sounds as if your friend backed off too fast for any chance of explanations. Is it possible that a third party might persuade her to at least get in touch and try to talk it out?