BritInOH, Your sitch seems to be much less severe than mine. But it is indeed complex/confusing: a WAW who wants you to move back in with her but she's still carrying on with OM, she's got low self-esteem and she's depressed. I don't know what to make of it but I haven't read every one of your posts either.
But it may be worth finding out just what part OM plays - as Kerry asks what is he supplying her that you aren't (he's not good looking, he's not smart, ...), is it a PA/EA? IS there something she perhaps is not getting from you that you could easily provide if only you knew? Would the approaches to dealing with depression/mental-illness along the lines in DR help - maybe you've already tried?
My 2c so far ...
Me-48, W-38 M14, D11, S7 W filed D 01/07 W had to move out 06/07 Current Thread