I am so sorry that you are going through this.
Your H established emotional intimacy with OW, and was willing to devastate your and your son’s lives. You learned of his affair from a third party.
Because your H is defensive and a closed book, you are stumbling around in the dark, unable to move forward. It sounds like you want to forgive, but you don’t know exactly what you are forgiving. You are suffering and he is continuing to hurt you.
Certain requirements are necessary for affair recovery. Your H doesn’t get to decide what you need to heal. A truly remorseful partner will do the following:
*He must answer all of your questions whenever you need to ask. He needs to do better than one word answers. In betraying you, he was treating you with contempt, and he still is. By being defensive and blocking you, he is trying to make you shut up and back off. Are you sure he isn’t still in touch with OW?
*He must accept your hurt and anger whenever you need to vent.
*You need full transparency on all devices, phone bills, bank statements, etc.
*He needs to completely cut contact with the OW, and if she is a work colleague, he should change jobs if possible.
Did you impose any consequences for his infidelity, such as having him leave for a while to experience how it feels to lose you? He needs to know that you mean business.
Please do not accept any blame for his cheating. To be unfaithful indicates that he has weak boundaries, poor coping skills, and a sense of entitlement to pursue an illicit ego-boost. Ideally he would seek individual counseling to investigate his weak elements that allowed him to cheat and learn ways to safeguard.
Hopefully in couples counseling you can address your needs for recovery, as well as your emotional needs in general.
You should also consider seeking the support of individual counseling to have a safe place to express yourself.