you are not responsible for him or his behavior. he is stalking you. he should respect your boundaries.
change your phone number and don't give it to him. get caller ID. don't let him into your home. don't talk to him.
he has no right to your personal information. don't feel you need to explain yourself to him.
please consider reading more online about this type of abuse and ways to be more assertive.
a great place to begin is this site:
http://www.drirene.com/victimpages.htm
check out articles on: (1) Borderline Personality Disorder ABUSE, (2) What is Abuse, (3) Anatomy of Abuse, (4) How to Cope with Abuse
another good website:
Abuse