Have you read "DivorceBusting" or "Divorce Remedy" yet? There are important techniques in there you'll need in the days, weeks and months (yes, I said "months") ahead.
NO BEGGING. NO PLEADING. NO PURSUING. It's all very counter-intuitive stuff, but you absolutely need to follow it.
It sounds to me like you have a long history of dysfunction in the marriage, to which you contributed greatly. I'm wondering if that finally reached a point where your wife reached out to (or accepted the advances of) someone else. There are some warning signs.
As for today, get the book and EAT. You'll have to force yourself to for the next few weeks, but your brain is going to need the strength.
