I would suggest right now you stop the confrontation about her talking with OM. You can't force her to move out and she is in the other room so that is good. Not surprising that she is angry because you are commanding respect. She expects you to cave in and give her what she wants. She will now try to manipulate you by throwing you little crumbs by saying "I need space to figure out what I want".
The truth of the matter is right now she is making decisions based on emotion (not logic and reason) and she is 100% sure she wants a divorce. There is nothing you can do to changes this and that is why you feel hopeless and powerless. Worst feeling in the world right? Unfortunately you can't change her feelings so the best thing for you to do is to keep your dignity and step aside at let this all play out.
Remember any relationship started and built on lies and deceit is sure to crumble at some point.
M:51 W:46 T:22 M:16 S:15 D:11
“Don't chase people. Be yourself, do your own thing and work hard. The right people - the ones who really belong in your life - will come to you and stay.”- Will Smith