Defamation case

Actually one of my female colleague is in trouble as she is suffering from emotional strain caused by the wife of the another male colleague. The case is like this that before 3 years the two colleagues started to converse on phone and through texts, but after some time the wife of the male colleague objected and created the scene of victimization and vilified both her husband and the girl at every level. Thus both colleagues took back foot and moved ahead with their lives. The relation of husband and wife was cordial too. But after a year the two started to contact each other again and it developed into a full fledged affair although no proof is there to claim so except the girls conversation with some of her friend. Out of no where that friend approached the male colleagues wife and cautioned her about the divorce that her husband is thinking about. Then again the wife started chest beating and the character of the girl was again assassinated at every front be it in office or home which lead to her mentally unfit and emotionally drained. She is not going to office, she is not interacting with anyone. Although we tried to pacify her but she is like I lost my everything for nothing. Again they(husband & wife) are in the process of reconciliation. Now my question is that can she(girl) file for defamation against the wife of her colleague? What are the legal provisions regarding this. Does it come under breach of right to privacy? What are the possible options under which she can sue her ? Waiting for your valuable legal advice Thanks