Don't be scared....
Whatever the outcome going forward, things will get better, honestly.
From the position of ten long years down the track, here's my thoughts.
I'm seriously impressed with the amount of introspection you've given your life, and the changes you've made to make it a better place - what a pity your wife went in the opposite direction.
If you could take the emotion of it for a moment, if this was a business deal, with a partner failing to commit to their responsibilities, what would you do? Buy them out? Dissolve the partnership?
R is long, it's hard, it has it's own pitfalls.
There are essential components to R, with the main one being two involved and committed partners. Truth and honesty are also non negotiable.
Right now, your wife is offering you none of the above. She is not being truthful, she is not being honest and she's still having an affair.
You have nothing to work with here, you cannot R on your own.
At three weeks out, you're still very early in the processes that we all go through. Resentment, anger, disgust at her behaviour.... doubt, mistrust... all take a very heavy toll, and are just about unavoidable.
Please don't make the mistake of letting your WS think she has the last say in what happens from here on.
With the benefit of hindsight, what I think would be a sensible plan for you, is to file for D (doesn't mean you end up D), separate out your finances, read and study hard the 180 (it's in the Healing Library, top left hand corner of the page) to make yourself stronger in dealing with this.
If your WS isn't sure about continuing in your marriage, then show her what life without your support will really be like. She might have felt like she wasn't getting what she wanted out of the marriage as it was, but she was still getting the comforts of it's benefits.
If the AP is married, definitely inform his wife, she has the right to know what is happening in her marriage too. Once the affair is not a secret any more and the need for hiding and deception gone, the A generally looses it's appeal, and of course, two sets of eyes on their behaviour is so much better than one.
As there are no children involved with you and your WS, then the general concern of breaking up the family unit is not there, it really is about what YOU want going forward.
I hope your WS comes round, I hope she has an epiphany and realizes that she has to fix this, but in case she doesn't you have to protect yourself.
Please take care of yourself, eat, drink lots of water, sleep... connect with friends, get out of the house and remember life goes on, regardless.
Hugs.