The Husband of my Sister-in-law want's divorce, been his fault.

Sir, I need your help & your suggestion's on the above subject. In short, my Sister-in-law want's to stay with Her husband. As usual tu-tu mai-mai is always there in a married life. But Her Husband is now saying in front of His Parent's & family, that He don't want to stay any more with His wife (my Sister-in-law) after almost 6 years since married. He is also saying to Her to leave the House immediately. Now He don't want to see Her face also. Earlier he had an affair with a Spinster. He works in night shift. Many times He goes out of the House without informing any one & He is in many other fault's which i can tell you later on all in brief. Now He is blaming His Wife (a working Lady) for all small small thing in daily practical woman's life, like not to get up early, like not lending helping hand in his joint family, etc. etc. etc. My Sister-in-law loves Him right from School day's friendship & She don't want to leave Her Husband, being a good Catholic. Her Parent's are no more & now She is left alone by her-self. Now both of them are around in their early 30's. They have a Girl child, who is just 4 years old, studying in Jr. K.G. class. Many expenses are bared by the wife, since Her Husband earns less in a Restaurant. Kindly advice