I guess time is said to help for some. I think the actual ability to recover and to what extent depends a lot on the amount of past trauma the betrayed has experienced in childhood, in particular.
There is a good book by Susan Anderson entitled " The Journey from Abandonment to Healing" ( I think I got that right. Read it a long time ago).
She has a background in Neuropsychology, I believe. She explains how the amount and types of chemicals released in the brain from betrayal trauma is markedly different between individuals with little or no childhood trauma/abandonment and those who have a history of this in childhood.
I had an extreme reaction that has lasted. As mentioned, I was sexually abused at 11 . I, also, grew up with a very abusive, alcoholic parent.
So, I think my background had a lot to do with my inability to get my confidence back and inability to ever trust again.
One thing you might want to look at is whether your husband has had a traumatic childhood in some way. He might consider therapy, and it might give you some idea as to his ability to recover and to what extent.
Realistically, as I unearthed a lot of repressed trauma through therapy and read the book, I realized that I was done and there was not a thing I or anyone else could do to get my confidence back.
It was not a question of being able to forgive. I have forgiven my abuser, my parent and my XW ( despite their never having acknowledged or apologized. )
So, maybe start there, his childhood to see if there is hope.
As far as practical suggestions, I think others have given some good ideas. But, realize that what works for another may be completely ineffective with your husband.
Try to think, really be honest, do you think that if he had done this to you, is there really anything that could be done that would make you believe you were your husband's s first choice now? Wouldn't you always question whether the renewed allegiance was a response to consequences or buyer's remorse vs genuine desire and value of you for yourself?
I think that many people who cheat fail to realize that they have crossed the Rubicon if their spouse has certain vulnerabilities from past trauma.
In many ways, the pay for reconciliation services businesses do the prospective cheater a disservice in promoting the idea that only a small % of marriages fail to survive and that in a lot of cases, the marriage is improved post cheating.
Anecdotally, based on lots of interactions with betrayed spouses, I do not think that is true. I think many marriages are damaged beyond repair, as is the betrayed spouse.