We understand your concern and are here to pray and counsel with you regarding this difficult situation. We must remember that God desires that all people treat each other with kindness, love, and respect. Verbal abuse is not only hurtful but also against the teachings of our Lord Jesus Christ. Let's turn to the Word of God for guidance.
1 John 4:20-21 (WEB)
If a man says, I love God, and hates his brother, he is a liar; for he who doesn't love his brother whom he has seen, how can he love God whom he has not seen? This commandment we have from him, that he who loves God should also love his brother.
Ephesians 4:29 (WEB)
Let no corrupt speech proceed out of your mouth, but such as is good for building up as the need may be, that it may give grace to those who hear.
Ephesians 4:31-32 (WEB)
Let all bitterness, wrath, anger, outcry, and slander, be put away from you, with all malice. And be kind to one another, tenderhearted, forgiving each other, just as God also in Christ forgave you.
Let us pray together for your sisters and their husband.
Father, we come before You in the name of Jesus Christ, asking for Your intervention in this situation. Lord, You know the pain and strife that verbal abuse causes, and we ask that You convict sister A's heart and bring her to repentance. Help her to see the error of her ways and to turn from her harmful behavior. Grant her the grace to seek forgiveness from her sister and brother-in-law, and to work towards reconciliation and restoration.
Lord, we also pray for the sister and her husband who are enduring this abuse. Grant them the strength to forgive, as you have instructed us to (Ephesians 4:32), and to love sister A as You love us. Help them to set boundaries and to respond in love, not retaliation.
Father, we ask that You bring peace and healing to this family. In the name of our Lord Jesus Christ, we pray. Amen.
We encourage you to continue praying for all parties involved and to speak the truth in love to sister A. It is crucial that she understands the seriousness of her actions and the need for repentance. Remind her that God's grace is sufficient for her, and that He is willing and able to forgive her and help her change her behavior.
Lastly, it is very important that we always remember it is only by the name of Jesus Christ that we can come before God the Father.
Acts 4:10-12 (WEB)
... let it be known to you all, and to all the people of Israel, that in the name of Jesus Christ of Nazareth, whom you crucified, whom God raised from the dead, in him does this man stand here before you whole. He is 'the stone which was regarded as worthless by you, the builders, which has become the head of the corner.' 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!