Remember that she once said that she loved you, then claimed to change her mind. Moving in with OM will actually put them in a pressure cooker of reality.
On the other hand, I've been following your sitch since you were in Newcomers, I saw your great pain there prior to and just following the D, and I wouldn't fault you in the least if you threw in the towel.
But what about merely throwing down the rope, Hope? Maybe just truly letting her go in your heart, and getting on with your life, including dating. If you're not ready, you're not ready, but even lunch or drinks with OW would be a fun way to stretch your social skills a bit.
The move-in sucks - I know. But it might be so much more informative for her now to see you with a nice 'who cares' look on your face that denotes that you are moving on and not looking back. Whether you leave the door cracked open or not is up to you, and can be s/t you keep secret deep down in your heart.
