Krathos,
I know believe me. I am not okay with my H pretending to be roommates with the OW. It is hurtful what she is doing, but I can see clearly she is afraid of disappointing you, letting you down. Yes she wants to be your friend, but friendship often leads to much more. I do believe rebuilding has to start at the friendship level and as she trust you more she may open up. It is not easy to accept friendship knowing you want more.
I will tell you that she is taking advantage of your character. That's okay, people always take advantage including our spouse. That doesn't mean you do not take this opportunity to grow the bond that is still there between you. These talks, these interactions will unnerve OM eventually. As your friendship grows, her arguments will intensify with OM. Let him dig his own grave and cause the demise of his relationship. The friendship needs to blossom for so many reasons, dont shy away from it because you want more that comes in time. Graciously accept and appreciate the small things that are happening. People often overlook the small things, we want a restored marriage like yesterday. it doesn't work out that way usually.
I know you dont want to get your hopes up, but you must walk on faith now. Do not be anxious about anything but in everything. I hope this makes sense.
Denjef31