Is she still with OM?
Even if the answer to that question is no, if she's doing nothing at all on her end to facilitate communication and show you that this is not what she wants, then you are most likely correct in that she's already checked out and is not going to turn it around.
That said, even if she did, what would you want? We spend so much time in the beginning worrying about what the wayward is thinking and what they need, we essentially ignore ourselves. I think that's where you will find your answer - when you stop worrying about her and start really thinking about whether, after all of this and a period of true NC, you could ever think about R. Read in the R forum for a bit and you wil see what a tremendous amount of work and pain is involved. Could you really see yourself doing that? IMO, the BS is so shocked and thrown off kilter that our fantasy in this scenario is to just put it all back together and have life return to normal. That's a big fantasy. Life, as you know it, whether you R or not, is over. A new normal is going to emerge and you have to decide if you want her to be a part of it.
My situation was a lot like yours. After a couple weeks of him doing nothing at all to talk to me or even act like I was still alive, I knew what had to be done. He chose to erase me from his world and the pain was unbearable. He forced me to file because his life wasn't going to change one bit whether we D or remained S forever. As along as he no longer had to deal with me, he was fine. I wasn't willing to be on the other end of that kind of constant, horrific disrespect. I decided to D because he gave me no choice and I realized that I was hanging on to something that didn't exist anymore.
I'm sorry you are hurting like I did and that she is insensitive and cruel enough to force you to take charge of a situation that she created. There's no saying you have to do this immediately. As long as finances and kids ( if you have them ) are protected, you could stay like this for a while. At the same time, filing helps you to feel like you took back some of your power because God knows she took it all away when she decided to make a unilateral choice about your future.