I wish you luck in your journey toward R. I don't know how your WW is feeling or what she's saying these days, but if she's quit the job, established NC with the OM, is giving you total transparency, and is showing signs of remorse, those are all good things.
At this point, you're pretty new to the game. It will definitely be a roller coaster with all sorts of feelings and thoughts that will crop up at all times of the day or night. For that, hang on tight.
Just know that you didn't force her to cheat and to keep an A going right under your nose for more than 2 years. If there were problems - and there are in every marriage - she had the choice to come talk to you. She had the choice to try to convince you that it was bad enough that you needed MC or else she was going to end it. She had the choice to just leave. She had a million choices of a million different ways to go about handling her personal business, but she chose the worst possible option.
I didn't get the chance to R. But, I've been around these boards long enough to know that this is a process that is going to take a long, long time to move through. They don't say the recovery time is 2 to 5 years for nothing.
For now, commit to IC and MC and see where things go. If you find that you can rebuild your M and find true R, that's fantastic. If you find that you just can't do it and that her A turns out to be a deal breaker, that's okay too. You're in control and you now get to have some say so in where this marriage goes.
Take your time, take care of yourself, and keep coming here. No matter what, SI makes you feel confident that you are not alone in this mess.