Prayers for family healing

I am asking for prayer for my brother and his children (18, 15, 12). About 4 years ago, he went through a nasty divorce with his children’s mother. Next weekend, he is getting married to a wonderful woman who loves him and his children. What should be a happy time has been nothing but stressful. His ex-wife is turning his children against him and spreading rumors that he is a terrible father and a dead beat dad. I am asking for prayer that he and his children can mend their relationship and get past the negativity that has occurred.