Your sitch seems pretty familiar to a lot of us - me included.
I also got a lot of the same surprise announcements - married the wrong person, our M has never been good, etc. - and then snooped and found an OM with whom my W was seriously trying to start a new R.
It is really hard, but know that you can't compete directly with the OM - your W is infatuated with the fantasy of life with him (mine sure was / is) and a fantasy is PERFECT.
I am now in the same place as you (and SoTireda) - but maybe a bit further along. I think the EA is over, but my W is not over it, and we are working out how to live in the same house. The good thing is that my W has stopped talking about D. The bad thing is that she has basically stopped talking. What I am trying to say is that things get better, but it is not quick and it is not easy.
What everyone is say here is absolutely true - focus on yourself. So easy to say, but so hard to do. I have found that the more I focus on my W - what is she doing? what is she thinking? are things getting better? etc - the worse things get. Find out what it is going to take to make you strong, happy and independent -- and do it!
Good luck and keep posting - I'll keep following along.
Me 42, W 39, S8, S6, S2 M 11y, A & ILYBNILWY 11/08 Walking away from a bad situation.
