Oh OP I'm so so sorry.
It's a horrible truly shitty situation.
My stomach was churning as I was reading your updates so goodness only knows how you were feeling.
But as others have said. The 1st thing you do is get some real life support around you.
Do NOT keep his dirty little secret.
My biggest regret was not telling people sooner and having to deal with it all on my own. Don't do that to yourself.
And he's following 'the script'.
i.e. re-writing history. Hasn't been happy for years etc...
Pay no attention to that.
It's bullshit. Something he's telling himself to justify his awful, disgusting behaviour.
You won't know how to feel. You are currently in shock.
The adrenalin will keep you going for a while but not forever.
You will crash and to handle that you will need to keep yourself hydrated and your sugar levels up.
As I always say, I couldn't stomach eating solids so sugary tea and ice-lollies got me through the 1st stages of this.
Please do see a solicitor.
You won't know for a while but you may not want to live in the house.
You may want a clean fresh start.
For now you'll want to hold on to everything, but that can and will change in time.
RL support.
Solicitor.
Try to keep busy. Get out and about. Go and see people.
Since my more recent split, middle of February, I've had only 1 free weekend.
So get some dates in the diary.
Lastly - step away from facebook.
We all do it but it's really not worth it.