We are truly saddened to hear about the struggles you and your family are facing, especially the behavior of your dad and the pain it's causing your mom. We will pray for your family and also provide some biblical guidance.
Firstly, it's important to remember that God's word tells us to honor our parents, as it is one of the Ten Commandments with a promise. For you to honor your father does not mean approving his actions but to respect him. The promise is a long life as seen in Ephesians 6:2-3 WEB:
"Honor your father and mother," which is the first commandment with a promise: "that it may be well with you, and you may live long on the earth."
It's also crucial to remember that God's answer is not to find a new spouse but to restore the marriage. Your mom's love and prayers for your dad are powerful, as seen in 1 Corinthians 13:7 WEB:
"Love bears all things, believes all things, hopes all things, and endures all things."
Now, let us pray together.
Dear Heavenly Father,
We come before You in the name of Jesus, lifting up this family that is desperately in need of Your intervention. Lord, we pray for this dear mother, who has been so hurt and unloved by her husband. Please bless her greatly, fill her heart with Your peace, joy, and love that surpasses all understanding. Strengthen her, Lord, and help her to endure this trial with grace and forgiveness. Please help this father that has gone astray. We pray that just like the prodigal son, he will come to his senses and return to You and his family. Lord, expose any sin in his life that is causing this destructive behavior, and bring conviction upon his heart. We pray for the restoration of this marriage, that it will be a testament to Your faithfulness and redemption. Lord save this man as described in Acts 4:12
"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!"
We also pray for this dear child and their sisters, that You will give them comfort, strength, and wisdom beyond their years. Help them to honor their parents, even in these difficult circumstances. Lord we ask this in Jesus Christ's name.
Finally, we encourage you to continue praying for your family, and remember that God can turn even the most hopeless situations around for His glory. Stand strong in your faith, and trust in the Lord with all your heart. As you said your dad uses his phone constantly, that is not good if he's finding things on it that are drawing him away from God. The source of his behavior is probably linked. Whatever is drawing him away from God should be removed by God for his and everyone's good. It's not your responsibility to fix but God's. Trust in the Lord's timing. The Lord knows what's happening even before you ask for help. Whatever you ask in Jesus' name according to God's will he will do it.