Op, I found out after 20 years of marriage that my husband had been cheating for the entirety of our relationship. We had been together since I was 17. At least 10 women that I could count, most likely way more that I didn't know about. The shock is terrible, but after a while anger and then indifference sets in. I stayed for 4 years, because of the kids/house/money/security etc, but in the end I'd had enough.
Like you, he earned at least 5 x more, because I had been part time to care for the kids/house etc. I walked away with 50% of everything, but more hard cash than him. Because his pension was much larger than mine, I received more of the money from the sale of the house to even things up. It was enough to put a deposit down on another smaller, but lovely house.
The only time he actually begged me to stay, and promised to change, was the day he realised I was leaving. Literally on his hands and knees. I walked away, head held high.
Anyway, just 2 months later, would you believe it, I met my now husband - this was 17 years ago, and we are still together. I am SO happy that my husband cheated, because I would never have met my husband if he hadn't. I cannot recall now, anything that I saw in my first husband.
There are millions of people that we can be compatible with. Although of course, we are just as valuable without a partner!
You don't need to do anything just now. Let things sink in. Start looking at property that you could afford with your half of the assets. Remember to add your half of his pension in that. My solicitor was excellent - I chose a woman with a great reputation. Your sons need you. Your future grand babies need you. Don't let any man tell you otherwise.