You know exactly what to do.
Don't sign the papers.
Don't get a lawyer yet.
Act As If.....you need to decide what that is.
She's snippey because she does feel horrible about this. You have created doubt in her mind.
Continue like you have been and create even more doubt.
If she wants this, let her do ALL of the work, do not make it easier on her. And if she wants to live without you, make it clear she is going to have to leave, not you.
You are doing well.
Stay the course and we're all here for you.