Wife now gets accused of slander by mistress?

There is a situation where a married man has done some really bad stuff with his teacher mistress. His superior at his work suggested that one of his colleagues should email all their colleagues telling them what a deadbeat dad and adulterer and irresponsible morally corrupt cad he is.I think he and his mistress are filing reports to the police saying his wife and children are slandering him. They are threatening the wife and kids. The husband gives no money to the family and I think has deserted them. He is travelling all over the world with his woman. The wife is terrified of him and of his threats and a lot of his colleagues are I think disgusted by his behaviour. She is afraid to divorce him as he has made these threats. His children hate him for what he has done to their mom when she was ill. Is the mistress able to sue her for libel and defamation of character, because she is a teacher? Is the husband able to use all this in a divorce case to damage his wife and kids