Gordie, she's not going to get past the "i'm moving out" part of the conversation, written or spoken. She also isn't going to be capable of comprehending something more than a few sentences long. I think Mach has given you a good blueprint: lead with what she wants to hear, building consensus, then tell her what she's hoping to avoid, then finish with a positive. Short, sweet, direct.
Good luck Gordie, and don't over-think it too much. What would you tell one of us, were we in your sitch?
xoxoxo
M 20+ T25+ S ~15.5 (BD) BD 4/6/15 D 12/23/16
"Someone I loved once gave me A box full of darkness. It took me years to understand, That this too, was a gift." ~ Mary Oliver