Done lurking, need advice.

[Grmpy_Mnky]

Background:
This happened once three years ago. She became very distant and detached. Concerned, I asked what the problem was. She told me she was unhappy and could no longer live with me because I was general unhappy about “everything”. I talked her into a couple of joint sessions with a MC. There she again related her dissatisfaction with my depression and anger. Following the second session she declined a third and told me it was over. Fortunately, she was able to get a detail down to the U.S. Virgin Islands (we both work for the National Park Service) which helped. She had space and time to reflect. We spoke very little while she was gone. After three weeks she returned. I picked her up at the airport and she gave me hug and a kiss and told me she missed me more than she thought she would. We reconciled but never really faced our issues.
Three years later I noticed the same signs. Again, anger and depression drove here away for the second time. My 180 thus far: Lose weight get into better shape – I know my weight gain bothers her and makes me feel worse about myself. I began IC, this has been a big help. Finally visited a Psychiatrist and changed my meds. Don’t get the wrong idea, I was never angry to the point of breaking things or anything physical. We fought infrequently maybe three times a year. However, during our fights I almost always would end it with a very “poisonous tongue”. The IC, books, and meds have helped this, but it has only been a month. We shall see if the changes are permanent. Now I feel like they are because this has been a wakeup call.
She offered to leave first. I asked her to stay in the house with our two dogs. I offered to get another place. Right now I am just a reminder of the bad times when she sees me. I figure if I move and go dark it may help things. She also told me here folks are coming for Christmas and I need to find somewhere to be the week they are here.
Here is a little more about our dynamic prior to the separation. We work together. That means we share our 30 minute commute, work in the same building, go to lunch together, ride home together, live together, and share the same bed. We were always together. She has very few friends and no friends here in MS. She also has an untreated neurosis. I do not know if it is depression or not. She just started IC. She is very stoic and normally keeps thing to herself.
Needless to say I feel very confused, betrayed, and scared as hell.