How can we stop harassment of a girl by her ex-partner?

Hello, This particular problem is been going on for almost a year now and I want to know what are the possible solutions for the same.Any kind of help is more than appreciated. A year ago,I met one of my old friends after six years.She was in a relation since two years but was unhappy with that guy.He had a criminal background and used to treat her in a very bad way.I started liking her and I told her so.Even she had started feeling for me the same but was afraid to breakup with that guy because she thought that he may cause problems to her and her family.Some months after she told him that she wanted to stop it but he threatened to come her home and create a scene.After that she started ignoring him but he threatened that he will commit suicide if she left him and she got scared.She tried to make him and his family understand that she is not happy with him but the blamed her for everything.This kept going on for months,she kept trying to make her understand and he kept torturing her and stalking her and even threatened to kill her.A month ago he saw us together and created a scene.I tried to make him understand the situation but was of no use.After that he is continuously messaging on Facebook,calling her family ,asking to meet her.She is now staying at her Aunt's place because of him.He even goes there and stays nearby that house.Even her family tried to make him understand but he didn't listen.Her family is not taking any action against him as they think its her mistake as well and they are just asking her to wait. I am worried for her now and I want to stop this.I just want to know what are the possible solutions for this.If she lodges a police complaint , will our relation affect that complaint in any way? Will it be fine if I support her in the police complaint or her family is a must in this case? What are the other possible solutions?? Please Help!