This is similiar to the way my W was acting when she left 2 weeks ago. All I can say is to play it cool from here on out. Things changed immediately when she moved out (probably in most part because I began to heed the advice of robx, Coach, Puppy, et al.). It was a scary time for me, but I learned I can handle myself on my own pretty well.
I started feeling better shortly after she moved out. I think that is in part what scared me. I thought "If I am able to handle this as well as I am; she must be on cloud nine." But I am finding that is not the case. Hang in there.