Mental Harrasment on women

My friend's father passed away a month ago and for that reason, the family is so disturbed.And a guy who she considers her friend started torturing her mentally and blackmailing to an extent that she tried to attempt suicide, that is because she does not want her mother to know that in this critical situation and she begged him not to take anything infuriating, however he does not have proper knowledge of what happened and states that she had a physical relationship with other and using unforgivable language towards her and her dad(late). She could not take it and shouted on him, then he started going to her friends and stating false things just to make them go away from her. She kept begging him not to do anything as it is a tender stage after parting of her father, but he didnt care to listen and stated that his only intention was to make her suffer and not live peacefully, and also he does not want her to meet him(her best friend whom she feels most secure with and cant afford to leave him at in this chaotic situation). The main reason for that guy to interfere is that she hugged her best friend as she was in grief and needed support and he has a problem with she hugging him as he said that he was loving her past 4 years(Despite she mentioning not to gave any hopes on her). He is behaving psychotic now . The main problem here is, this is not the right time as there is no family head anymore and does not want it to go public (neither to her mom as she might break down). We have all the proofs of his mental harassment and want to warn him that if he creates any further problem , his graduation will be stopped from a well known professor(as we do not wish college administration staff to make it public) and also want to go make him answer everything in front of their family and make everyone sign a bond as to make sure that he does not interfere in her life again and in case he does , he will be imprisoned. So here i request you to provide some information about IPC sections or mental harassment sections and some advice what to do and a statement that whether we are doing the right thing blocking him do any further. Thanks in advance