It's a really big change op, it's not surprising that it's scary and unsettling for you.
You seem to be saying that if he went off with someone else and proved to be a better partner, you'd be missing out. Let's unpack that a bit.
He's abusive and exploits you. That's not a passing habit, that's something that expresses a deeply held belief about how power should be distributed in your home. A lack of respect, an unwillingness to consider your perspective, an unwillingness or inability to control anger.
How would all those things change if he had a new partner? Typically men like that are all sweetness and light with a new partner - to begin with. Then they fall back into the old ways once they think they have a woman attached to them/financially dependent/no self esteem or support network etc. In short: he's not a great catch. Abusive people can learn to change their ways but it takes a recognition of what's gone wrong and a willingness to change. It doesn't happen overnight.
While you're looking at his sm and thinking of his future, what about yours? What do you want in your future? Get paper and pen and write down anything that comes into your head about your career, how you want your kids education and upbringing to be, your home, your hobbies, your friends and relationships. You're more than just a wife. You have potential and a future. Maybe even with a partner who treats you well, at some point.
You need help and support to get through this, this relationship is a major part of your life and you can bet your husband and your family will soon be pressuring you to go back to how things were. If you don't want that, contact the freedom programme and the organisations listed above to get support, someone to talk things through with, practical advice on finances etc.
In the meantime, you're in shock and it's hard. Reach out to friends if you can. Take care of yourself - not doomscrolling on his sm, make sure you have good food, rest and exercise.
Good luck, I'll be thinking of you!