What is the Sharīʿah ruling concerning a wife who slanders another wife, describes her and her children with abusive language, and assaulted her home, and what should the wronged wife do about this and about her husband who does not stop the offending wife?

What you mentioned about this woman's abusive and harmful language is a reprehensible act and impermissible, for the Prophet, peace and blessings be upon him, said: "Insulting a Muslim is فسوق (disobedience/wickedness), and fighting him is kufr (disbelief)." We advise patience, for in it is expiation for sins and elevation of ranks. We also advise making supplication, such as: "O Allah, we place You against their throats, and we seek refuge in You from their evils." It is possible to seek assistance from those with influence to advise her. The husband should also discuss the matter calmly to address it and ward off her harm from you, such as looking for a residence far away if his financial situation allows it. He must support you and repel the injustice from her, because supporting the oppressor is by preventing him from oppression.