I’m going to be kind of blunt here. Please forgive me in advance.
Your H had a 2 year A! He hid this from you for 2 years! Which involves some pretty serious deceit. And implies a pretty serious lack of morals .
Somebody who is capable of that has serious issues that goes beyond a SSM. He has a lot to overcome before he can build a healthy marriage with you. To be able to fundamentally carry on a 2 year love affair with his wife and young kids at home, he needs to do intensive work and have intensive remorse. And not see this is a good thing in any way.