Uncanny how closely your sitch resembles mine, even down to the TIMELINE. I got the 'bomb' from my W in March 2010 as well. Was unhappy, had fallen out of love, moved into spare room, said she wanted to separate. I knew she was unhappy - we BOTH were, but I never dreamed she had reached such a desperate point. LST, I took it as a shovel to the side of my head and took full respons for my behavior, recommitted to her and our family, told her she was right and whatever time and space she needed was OK. It was hard, but after several weeks, it WORKED! She came back to our BR and for about two months, all was well. Then in late summer, in a nutshell, she changed her mind again. I pleaded with her and did everything I could to stop her, but she was unswayed and moved out Oct 9th. So I'm a couple steps beyond your sitch, I think, and pray it doesn't go that far for you. I am trying my best to stay true to the DR approach, resist my feelings of despair and longing for her, but MAN it's hard. The holidays were horrible and I do NOT want to have to go them again like this.
Tell me more about what led your wife to her 'state of mind.' Mine was a new job, working out of the house for first time in 11 years, better salary, etc. Classic MLC, but she isn't showing signs of thawing and the pain is unbearable.