I noticed that my H does the same thing. He likes to flip the board on me and this makes me question my sanity...well, memory...sanity sounds more dramatic so I'll go with that. I can't believe the person he is turning into or is being right now--dishonest, petty, manipulative... Oh, i'm sure she can come up with more crazy stuff. You know what you tried to do. The hard part is getting over the fact that your effort was not received in the way you wanted her to. Naturally, this makes you feel like it's your fault--that you could have tried harder. Don't get caught in this mindset.
Dealing with the "work friends" is tough for me too. Your W will tend to gravitate towards those who favor a "yes" stance on her situation. It's unfortunate but just pray (if you're the type to) that she will be convicted. Frankly, she is otherwise she would not feel any sadness. So, even though the emotions she is feeling or expressing towards you are negative be thankful that she's feeling anything at all. Okay, not thankful but hopeful. This shows an internal struggle and that 's good. If you think about it...how much more would you appreciate it if she was completely emotionally removed from the situation? As if all feelings have been replaced or invested in someone else? I think this would hurt more. And, once she has broken that line of trust between the two of you, there isn't anything that's off limits. Which means, she is so out of it that she will expose the most intimate details of your R to get anyone to side with her and justify her actions. My H is doing it too.
I know that the "friend" role is not as comforting right now but it's not necessarily bad either. I suppose how you approach the friend thing is what makes the difference. Friends can be lovers...eventually. So, try looking at it from that perspective rather than the other kind of friend that is completely devoid of any romantic potential.