Again you are at a critical point to possibly turn this around quickly. The only thing you state is that you will NOT live in an open marriage and you need her to move out so you can have time and space to figure out what you want.
Do not ask her what her goal is for the separation. It's to pursue a relationship with the new guy to see where it goes. The longer she knows your plan B the more time she has to pursue the new relationship.
Do not ask her if she has made up her mind. She hasn't but if you ask her she will know you are attached.
You can't control what she is going to do but you can communicate what you won't tolerate. You have to set clear boundaries that if broken bring upon extreme consequences.
