Sucide

My Sister (37 years) was in relationship with a Boy (35.5 Years) for last 14 years (moslty long distance relationship) and she got to know that Boy was in relationship with one of his colleague for last 2 years almost so she confronted him but boy was very confused with whom he would like to go ahead so he was talking to both though my sister started making some distance but still had a hope that he may go ahead with her and marry her. Boy's Parents were not ready for the marriage. Boy was intelligent and was doing Phd but due to bad luck he couldn't find Good job OR expected results for higher studies. He used to apply for jobs at some many places. He applied for Jobs and higher studies but couldn't get positive results so was in depression and used to say I'll commit sucide. And wrote an email to my sister and mentioned that i'll commit sucide and neither you or my famly memebers are responsible for it but that time my sister thought he is dipressed so convencided him and made him clam. And after around 2-3 months as soon as he got a result for his heigher studies entrance exam and couldn't make it. He committed sucide. Now local Police closed the case considering sucide case but Boys family members call my sister and blame her for his sucide and call her again & again. And Now his father wants to meet face 2 face. Please suggest what should we do, Can they file any case against my sister? please suggest