Curing Narcissism is difficult unless the person can admit that they have the problem and are willing to submit to therapy for however long it takes. It can be a slow process, but it can be done as long as the person can focus on being aware of their low self esteem and how their behavior affects others.
If your husband wants to rebuild trust, here are some steps to take:
One, is he sorry for what he did
? This is important, because if he does not take responsibility recovering the relationship will be difficult.
Two, has he stopped all contact with the other women? He needs to so as a first step to regaining trust.
Three, are the two of you talking about what happened? He needs to be open and honest about what happened and let you ask any questions you need to.
Four, he must be transparent. That means telling you his whereabouts, letting you see his phone, email accounts, etc. He needs to be open with you about his life.
Five, have someone from your church be his "accountable" person. They need to direct him back to his faith and be there for him when he feels he may fail.
If he can do these things, then he has a good chance of overcoming this issue.