how long has she been there? maybe she might start to get that alone feeling. Is the OM moving in also? If not maybe now that they can be together 24/7 the party might be over. Sorry your feeling down. My W has not moved out so I can't totaly relate but from what I have read in other posts. Just because our S move out it's not over many have moved back.
I'll keep my fingers crossed for you
H
And if I claim to be a wise man, well It surely means that I don't know