Need Proper Guidance To Marry A Committed Person

I'm in love with one guy and even he loves me in the same way and we want to get marriage but in past he was hospitalized due some bad health condition that time his ex girlfriend helped him a lot to recover. She used that situation and put a condition to marry her after getting out from hospital, that time for his family no was there to support so they agreed and gave a promise to her and her family. After coming out from hospital he got some torture from her, she started to control him in everything which made him to move away from her and fell in love with me. He told her that he is loving me and he can't marry her. Now she is not ready to move away and she is threatening him saying if you marry her ill suicide by writing whole your family names and send him to jail or she will do something to me if he talks to me or try to meet me. Now what we can do here to get protection from her and get marriage without any problems. please suggest.