I would definitely check out the Midlife Crisis forum here on DB.

There are other forums as well that specialize in helping people who are struggling with their spouse's crisis. You might find links to them in the MLC forum.

Me: 44, Wife: 39
M: 17 years T: 20 years
Bomb on 08/25/09
1/13/10: MC started
1/28/10, 2/8/10: More bombs
8/28/10: Wife moved out
No talk of D, no movement

"Every day is another chance to get it right."