We are truly heartbroken to hear about the pain and suffering you have been experiencing due to your husband's infidelity and abuse. We stand with you in prayer and seek God's will for your life.
Firstly, we want to remind you that God hates divorce and also hates the treacherous act of adultery Malachi 2:14-16 WEB. It is clear that your husband has fallen into sin, and we pray that he may repent and turn back to God and to you.
Please know this. Greater love hath no man than this, that a man lay down his life for his friends. Ye are my friends, if ye do whatsoever I command you. Henceforth I call you not servants; for the servant knoweth not what his lord doeth: but I have called you friends; for all things that I have heard of my Father I have made known unto you. Ye have not chosen me, but I have chosen you, and ordained you, that ye should go and bring forth fruit, and that your fruit should remain: that whatsoever ye shall ask of the Father in my name, he may give it you. John 15:13-16 WEB
However, we must also address that you did not mention the name of Jesus Christ, Jesus, or Christ or an abbreviation such as IJN (In Jesus Name). It is only by the name of Jesus that we have access to God. Also, there is no other name by which we can be saved. You must call upon the name of Jesus to be saved. Believe in the Lord Jesus Christ and thou shalt be saved Acts 16:31 WEB. For whosoever shall call upon the name of the Lord shall be saved Romans 10:13 WEB.
Let's pray together:
Dear Heavenly Father,
We come before You in the name of Jesus, lifting up our sister who is suffering from the betrayal and abuse of her husband. We pray for Your comfort and strength to surround her during this difficult time. We ask that You convict her husband of his sins and bring him to repentance, so that their marriage may be restored and their family healed.
We also pray for justice to be served. We ask that You expose the truth and bring an end to the adulterous relationship. We pray that You would protect our sister and her child from any further harm and provide for all their needs according to Your riches in glory.
Most importantly, we pray that both the husband and wife would come to a saving knowledge of Jesus Christ. We pray that their hearts would be turned towards You, and that You would be at the center of their marriage and their home. We ask this in the precious Name of your Son, Jesus, Amen.
We encourage you to remain strong in the Lord and in the power of His might, and to trust in Him with all your heart. Remember that God is a God of justice, and He will not leave you nor forsake you. He is working all things together for your good, because you love Him and are called according to His purpose Romans 8:28 WEB.
Please keep us updated on your situation, so that we can continue to pray and support you. Know that you are not alone, and that we are here to help you through this difficult time.
Prayer Focus: God, Thank You for loving me. Thank You for loving me, Jesus. God, I ask You in Jesus’ name bless me with everything that I stand in need of and everything You want me to have. Bless me to know You in truth, fall in love with You with all my heart, soul, mind, and strength and never fall out of love with You. Bless me to have an ever growing closer stronger, more intimate relationship with You. Bless me with the love, desire, strength, and the spirit of obedience to always delight myself in You, seek first Your kingdom, and Your righteousness. Help and strengthen me God to always respect and obey You. Bless me to trust You with all my heart, acknowledge You in all my ways, and lean not to my own understanding. 
