Strange I just skimmed your thread, and from what I read your sitch is alot like mine, with the exception that we have a child so there is about 2 or 3 times a week interaction.
What really struck me was what you said about her watching TV, and me (oops I mean you) on the computer. Pretty much the same here. I got wrapped in my stuff and she in hers, and down we went.
One thing I did, is that I did send a letter, and also told her in person. That I thought our marriage was worth saving, I still for the most part feel that way. It might be contrary to DB advice, but I felt it was important that I got that out there before I went dark. So.......basically I know I did what I could do, and the ball is in her court!........