Thanks for your thoughts. I'm okay and am actually glad she made a decision, even though it was a poor one. But I think everyone here knows why she chose the OM. "He appreciates what I'm going through (PhD)," "I have more in common with him (work)", "We just relate to each other better." Who knows, maybe they do work better together, but she and I have always been friends and able to talk about anything. Even in our worst moments we could talk. And that is still there, though she's ignoring it and doesn't think it really means anything. At least it makes it easier for me to move forward on DBing.
After all, she admitted to still caring deeply for me and that's been enough to make her move back in briefly despite her unwillingness to put energy towards R.
I know that part of this is a result of her C as well - sounds like he was pushing her to choose something and accept the consequences of that choice rather than constantly hedging.