This is a very difficult question, and the answer may not be a simple YES or NO. Christian marriage counselors are divided on this and we will look at their reasons from Scripture.

Those who say NO will point out that repentance and forgiveness in this case must be before God alone. Many point to King David (who committed adultery with Bathsheba) who, as far as we know, only confessed his sin to God. Let’s read of this is Psalm 51:1-4, “Have mercy upon me, O God, according to Your lovingkindness; according to the multitude of Your tender mercies, blot out my transgressions. Wash me thoroughly from my iniquity, and cleanse me from MY SIN. For I acknowledge my transgressions, and MY SIN is always before me. AGAINST YOU, YOU ONLY, HAVE I SINNED, and done THIS EVIL in Your sight” (NKJV). When David said “my sin” he was referring to the sin of adultery with Bathsheba. He then says that “this sin” was “against You only.” Surely David knew he had sinned against Bathsheba’s husband Uriah, so why would he say this? I believe David knew that sin is “first, and foremost, against God.” David knew that God had witnessed this sin for he also said in this prayer of repentance that he had “done this evil in Your sight.” Uriah had no idea what David had done, but God did. When David was convicted of this sin by the prophet Nathan he said to him, “I have sinned against the Lord” (2nd Samuel 12:13). So, in David’s mind, his sin must be confessed to God. Another verse that is used to support this view is 1st John 1:9, “If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.” This goes along with what we just saw in David’s confession; he confessed it to God, seeking His forgiveness and cleansing (see verses 2, 7, 10). This forgiveness and cleansing gave David a “good conscience” and thus he need not confess it to anyone else. In fairness, these counselors do go on to say that some sins should be confessed before men, but only if they are aware of the sin that involves them. They believe in the case of adultery if one confesses it to their spouse who has no idea of the infidelity, they risk a backlash that may result in untold suffering and possibly divorce.

Those who say YES will point to James 5:16,  “Confess your trespasses to one another…” If you commit adultery you have “trespassed against your spouse and you need to confess it to them.” They would admit that this sin is, first and foremost, against God and that it should be confessed to Him, but they believe the innocent spouse has the right to know that they have been sinned against too. Another applicable verse is Acts 16:24 where the apostle Paul said, “I myself always strive to have a conscience without offense TOWARD GOD AND MEN.” If we commit an actual trespass “against men,” we can only maintain a “good conscience” by confessing it to both God and the one(s) we have sinned against.

As I stated as the beginning, this is a difficult question and perhaps the answer could either be yes or no, depending on the circumstances. For example, if one has truly repented before God and experienced His Divine forgiveness and cleansing from this sin (real DELIVERANCE from any temptation to ever commit adultery again), along with a “good conscience,” it may be best NOT to tell your spouse.   Yet one may truly repent before God and know they are forgiven and cleansed, but their conscience still bothers them when they know how they grievously sinned against their spouse. In that case, it may be best to confess it to them in true humility, assuring them that God has indeed forgiven you and now you seek their forgiveness as well. No one knows how they may react, but no doubt emotions will be running high and it may take awhile before trust can be restored as well as sexual intimacy. And it may indeed cause such anger and mistrust, that they may seek to divorce you.  As you can see, I am NOT taking a stand and giving you a definitive answer, but I have prayed for the Lord to guide you in this weighty decision.   (DO)  (505.5)