Before you reached out to OM W Altair posted to you that when she outed A she essentially invited two other people into her R. What did you consider when you read that? Look, people giving you feedback have been there, and are basically giving you the script of what is to come, you need to really consider what you are being told when you read it.
I will tell you I don't have experience with this, I have never been contacted by OM W, but my thought is srop contact with her. Everyone needs to go on their journey, don't think you can control what their journey is. If it was me, next time OM W contacted me, I would politely say that I thought it best you knew what was going on, but I need to work on my self and I do not want to continue contact. She will do what she will do, not your monkeys, not your circus. I would not try and tell OM W if she should or should not confront your WW.
Also, why is your WW reading your messages? You need to stop giving your WW the idea your ok with her having an A, you need to stop being ok with it. Take your focus off wanting to save M, put focus on wanting to better yourself, you need to work on yourself... Step back from the craziness and really focus on you, get your boat stable.
M - 9 1/2 years 5/5/16 - Bomb drop - 3 week EA 10/31/16 - We sold house 01/10/18 - D Finalized