It's astonishing to see just how delusional someone can be. Even when I told her I knew the truth, she lied. I've never seen this before.
It is indeed astonishing to see, but it is not uncommon.
Like you, I had red-handed evidence that completely and unquestionably exposed the truth.
When I confronted my XWW, she denied and lied, and denied and lied some more.
Your wife, like my XWW, has been lying to you to avoid the consequences of behavior she knows is horribly wrong.
You were the very person who was never supposed to find out - but you did.
You were the very person she made the greatest vows to that she was supposed to protect over any other - she instead committed the ultimate betrayal.
She solemnly vowed to you that she would be honest and that, more than any other, you could bestow your unquestioned trust in her - and she willingly betrayed that sacred trust.
She wanted to avoid all the accountability of her behavior and now, forced back to reality, she is forced to face it.
Most people like this will resort to lying, even after getting caught, because it is easier than facing the ugly reality that their behavior created.
When the returns on lying diminish, then the blame shifting and excuses will likely come - be prepared.
My XWW, like your wife, also had a “friend” who supported, condoned, encouraged, and helped facilitate her affair and keep it a secret from me and our kids.
My XWW’s shitty “friend” was also having her own affair at the same time and my XWW was likely helping her as well.
Be advised, your wife is highly likely going to be spending much time with this “C” person because she will be offering your wife a buffet of comforting excuses and bullshit as to why all of this is your fault and that none of what she did would have happened if it wasn’t for you.
Any and all blame she attempts to foist on you or your marriage should be immediately, absolutely, and forcefully rejected.
Know this: NONE of what she has been doing has anything to do with you or your marriage - nothing.
Don’t even begin to discuss or debate anything sounding like an excuse or blaming you - just shut it down immediately.
I hope she is one of the very rare ones here that has a “what have I done?” epiphany quickly, comes completely clean and honest and is willing to move mountains to rebuild what she has destroyed.