We understand your urgency and passion, but we need to address a few things before we pray together for this situation. Firstly, we must remember that God's desire is for all people to come to the knowledge of the truth and be saved, not that we should pray for the destruction of others, even if they are worshipping false gods. As it is written in 1 Timothy 2:3-4 WEB: "For this is good and acceptable in the sight of God our Savior; who desires all people to be saved and come to full knowledge of the truth."
Furthermore, we must be careful not to engage in practices that resemble magic or spell-casting, as this is clearly forbidden in scripture. Deuteronomy 18:10-12 WEB: "There shall not be found with you anyone who makes his son or his daughter to pass through the fire, one who uses divination, one who practices sorcery, or an enchanter, or a sorcerer, or a charmer, or someone who consults with a familiar spirit, or a wizard, or a necromancer. For whoever does these things is an abomination to Yahweh."
Instead, we should pray for the salvation of this person, that they may come to know the true and living God through faith in Jesus Christ. We should also pray for unity and love between you and your husband, that your marriage may reflect the love of Christ for His church.
Let us pray together:
Heavenly Father, we come before You in the name of Jesus Christ, the only name by which we can be saved. We lift up this person to You, asking that You would reveal Yourself to them and draw them to faith in Jesus Christ. We pray that any false beliefs or idols in their life would be replaced with the knowledge of the true and living God.
We also pray for unity and love between our sister and her husband. We ask that You would strengthen their marriage and increase their love and desire for each other, as it is Your desire that a man and a woman should leave their families and become one flesh in marriage.
In all things, we ask that Your will be done and that You would be glorified. In Jesus' name, we pray. Amen.
Lastly, we must remind you that it is only in the name of Jesus Christ that we have access to God and that there is no other name by which we can be saved. As it is written in Acts 4:12 WEB: "There is salvation in none other, for neither is there any other name under heaven, that is given among men, by which we must be saved!" If this person comes to faith in Jesus Christ, it will be because the Holy Spirit has drawn them, not because of any action or prayer on our part, beyond our prayers for their salvation.
We encourage you to continue to pray for this person and your marriage, always keeping in mind the principles outlined in scripture.
Prayer Focus: God, Thank You. Thank You for loving me. 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, mind, soul, body, 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. 
