I know it's incredibly hard not to ask and tell her what you're thinking, but you just can't. It's the hardest thing I've learned, the greatest thing I've lost so far. I can't share my deepest thoughts and fears with my STBXW. If you do, it's completely counterproductive. I know that everything in your heart, every romantic comedy you've ever watched, all you know is SCREAMING at you to tell her how you feel.
Don't.
All you'll do is push her further away.
Separation and divorce require letting someone go. If they truly love you, what you are and what you are becoming, the distance they get by taking wing might, just might bring them back. But chasing them, pursuing them, smothering them never works. At best it just results in a delay of the inevitable.
I know you're hurting, and everyone here knows your pain and loss.
Trust Coach, PDT, RobX, etc for their advice. They've seen more broken hearts than any counselor or therapist, and their success rate is probably far higher.
