I suggest you find an apartment this week, and I will begin to consult lawyers.
I would say NEVER leave. Odds are better if she's in the house, like you said. She's leaving you, so she should leave the home. It can also have implications later if this does goto divorce, especially if there are kids. Do not leave the home.
Formerly SGfan M:38 W:33 M:8 yrs T:10 yrs Bomb: Dec '08 Separated: 4/18/09 Divorce: 8/28/09 XW Affair began: April 08