Hi Scrant, I can relate exactly how you feel. My WW moved in with OM about a month and a half ago.
IMO as well, the friendship is allowing the best of both worlds and will continue in limbo if you allow it. It is really an open marriage if you think about it. Some are okay with this kind of relationship and will wait it out, but I knew in my heart I couldn't do that.
In my case, because of the way my WW left for the OM, I told her we could no longer be friends while she was with OM and after divorce. I told her we would continue to be great parents to our S2, and work on co-parenting and logistics which is so crucial. But beyond that, no real friendship. One of the hardest paths I have ever decided on because I realized I may or may never have a close relationship with her again. But I just couldn't live in an open marriage.
Now there is limited contact (she initiates almost entirely) maybe a text message per week. Over time I am accepting this as the new reality, and focusing on S2 and I with trying new things and GAL. This is again just my situation and the approach I took. It took a month to make my decision on friendship of what I truly wanted (although I want to reconcile with WW, she told me she is done and moved on, so what choice did I really have... I can't change her so I could only focus on me and my emotional health?).
I guess through all this I wanted to share my story in a nutshell. It is true that while WW is in an A, they will not want to work on MR. This is a given, thus any signs of improvement you THINK you see are not towards improving MR... it is just cake eating.
The above advice from Fogg and Accuray are great. GAL is excellent and as I can see you are right into that.
You have tremendous support here and will get through this.
M: 33 W: 30 T: 14 M: 9 S2 BD: May/2015 (w moves into spare bedroom one week later) EA / PA (discovered): June/2015 W moves out (living with OM): Sep/2015