I don't understand why she is so nice to me, invites me to do things, and then at the same time is keeping om around and is so short with me when I text her about things involving D2.
IMO, I thing the WAS does this because it helps them feel less guilty about the hurt they are causing.
While I'd say based on your posts it seems she is at least questioning what she wants, you or OM, for now she wants to have both. As long as she knows you are still around waiting for her then she doesn't have to reflect and truly make a decision.
I know it's hard, and only time and detachment can help here, but do you think you can try going truly dark for a change? Interact with W as needed about your D2, but otherwise show her you're moving on with your own life.
I think WW needs to feel what it's going to be like losing you 100% if she chooses to keep OM in her life. Also, this will eventually make everything much easier on you in dealing with these emotions.
Me:36 W:30 M:2.75 T:7 BD: 4/2015 ILYBNILWY: 5/2015 W Moved Out: 5/2015 W filed for D: 7/2015