Eric Fromm wrote a book called the Art of Loving many years ago. He said in there, "true love is giving up one we love so that they might be happy with someone else". Wow!!!! Never forgot that. Talk about the epitome of Christian or Christ-like LOVE...
My fear for your wife is that it might be a rebound, but then I'm reading tween the lines you feel this was afoot before and partly a impetus to the breakup?
You'll get nowhere with that line of speculation, and even if she told you full disclosure and it was, there's nothing to be gained. You signed the papers. Love didn't go away in a day...
I know wars can be fought over the biblical aspects of divorce, but as said by others, wish her well, pray for her happiness and it will come back to you in blessings you cannot imagine.
Forgiving 77x7 doesn't mean it won't be the same issue, the same person, the same hurt...over and over...cause it can/will! We are ok. Wake up and it starts tearing at us again. Forgive again...and again...and again... till you are healed. Much for you as her...and it's what God calls us through Christ TO DO!
Not as hard as being whipped to the bone and nailed to a cross to die, but still pretty darned hard for most of us, me included...but it is what He asks.
You'll be ok. Again, embrace the anger, the hurt...then forgive as often as it takes for it to loose Satan's hold on you through those emotions!
God bless. Keep the Son in your eyes!