Can't imagine what your going through. Unbelievable really, but I've learned a WAW's actions can often be surprising. Your doing a great job processing all this, as it must be extremely frustrating.
From my own experience, I'd be careful hoping the MC will influence or change your W's actions. I've been in a similar position where I was hoping for the MC to step in, and she did, saying that there was no point in MC while the A was ongoing. My W simply said that she had no intention on stopping her A ( not in words like that, it was more wishy washy, at this time, I'm not prepared .....garbage) . And I also stopped it, as I was advised by everyone on the boards that it would not be fruitful given the OM was still involved.
Your W is definitely going to have to realize this on her own. Whether you remain there or not will of course be up to you. Great work so far, and good luck. Stay strong