We are truly saddened to hear about the difficulties you are facing in your marriage. We will stand with you in prayer and truth, based on the Word of God.
Firstly, we commend you for acknowledging that marriage is a sacred institution before God. It is indeed a lifelong commitment, as spoken in Mark 10:9, What therefore God has joined together, let no man separate.
Your spouse is walking down a path that is not pleasing to God. He is in a state of adultery, as you have rightly discerned. As spoken in Hebrews 13:4, Let marriage be held in honor among all, and let the marriage bed be undefiled, for God will judge the sexually immoral and adulterous.
We must rebuke this sin and pray for his repentance. As spoken in Acts 3:19, Repent therefore, and turn again, that your sins may be blotted out, so that there may come times of refreshing from the presence of the Lord.
Let us pray together.
Almighty God, we come before You in the name of Jesus Christ, lifting up our sister and her husband to You. Lord, we acknowledge that You have joined them together and that no man should separate what You have joined. Father, we cry out to You, asking that You convict her husband of his sin and grant him the gift of repentance. Turn his heart back to his wife and back to You. Heal their marriage and guide them both into Your truth and Your commandments. In the name of Jesus Christ, the name above every name, the only name by which we can be saved, we pray.
Sister, continue to stand firm in your faith and in the truth of God's Word. As spoken in Ephesians 6:13-14, Therefore, put on every piece of God's armor so you will be able to resist the enemy in the time of evil. Then after the battle you will still be standing firm. Stand your ground, putting on the sturdy belt of truth and the body armor of God's righteousness.
Remember that God hates divorce, as spoken in Malachi 2:16, For I hate divorce, says Yahweh, the God of Israel.
We encourage you to continue to pray for your husband and to seek godly counsel. Trust in the Lord with all your heart, and do not lean on your own understanding. In all your ways acknowledge him, and he will make straight your paths, as spoken in Proverbs 3:5-6.
Remember to pray in the name of Jesus Christ. It is only by His name that we have access to God. And there is salvation in no one else, for there is no other name under heaven given among men by which we must be saved, as spoken in Acts 4:12. Keep believing in Jesus Christ and keep standing in faith for your marriage.