Oh, Montreal! My story is so similar to yours, right down to the 12 years from the first DDay (that I know of) to affair #2. My XWH was the stay at home parent to kids now 22 and 19, and we navigated teenagers and Covid same as you, and then I got a big promotion and raise (like your XW). While I was doing that big new job, XWH was starting another affair, and when I found out last Christmas, I divorced him. The kids are with me and haven't spoken to their father since Christmas. I'm paying spousal support, so he's getting a nice "reward" for his infidelity...grrr.
Anyway, here are some of the perspectives I keep in mind, if they help you reframe:
I gave him 12 years that I can't get back, but I have my freedom from his toxic nature now, and I'm going to make the most of every second!
Instead of being humiliated by his second affair, it has empowered me. It let me walk away from the marriage with confidence, knowing I had done everything possible and more to make the marriage work while his actions were destructive. And if he had an ounce of self-awareness, he'd be humiliated by what he's done.
One difference in my situation from you is that my kids know the whole story (they are the ones who caught him in the latest affair). They couldn't be more proud of me for acting with integrity and strength. Have you considered talking with your kids, not in a "bash the ex wife" way but in a "here are some important facts) way?
After DD#1 I told no one except my sister, and I suffered basically alone. I wanted to protect WXH, on the assumption that he'd do the work and we'd successfully R. This time around, I've prioritized my own well-being. There has been no shame in telling friends, colleagues, neighbors what happened, and their support has been amazing. A simple "XH has been unfaithful, and I chose to divorce him" is all it takes. And if they ask about the kids, I say "XH has not contacted his kids since December." People are smart and fill in the blanks.
I posted a message the other day sharing that XWH and his new girlfriend (not the affair partner...he's moved on from her, too) ran into my daughter's friend at the ice cream shop where she works the other week. The second he saw the friend, XWH turned around and walked away without a word. The fact that a grown man can't face a 19-year-old in an ice cream shop shows that deep down, despite the shiny exterior and good-guy-with-a-new-girlfriend facade, he is ashamed of himself.
Wishing you success in reframing and moving forward from this difficult moment. From what I can tell, you've handled the situation incredibly well.