Just reading this I wonder if your W is having an MLC? My H seems to be going through all the stages, Anger, Replay, now some depression too. Maybe your W is in the Replay stage with the affairs she is having or thinking about? If you think so, you may want to check out the MLC section here and the resources thread.
I found reading about the stages of MLC to be very interesting and there is a chapter from DR posted about MLC that was esp. good also. If you haven't read DR, I highly recommend that of course! Hope you are having a better day today! I find keeping myself busy, spending time with the kids, and doing things I enjoy really helps! Karen