As a teen I read a book about a girl who was friends with a male vampire who then turns her.
They then have to hide her from others on the discovery that she has supernatural powers - I think psychic, or telepathic - passed down from her father's side of the family.
She had a little brother who knew what was going on, and her parents were separated. They went to school together, and the vampire had his own apartment. They run out of hope of finding help in their home town and go out of state to find help from a group of witches.
What book is it?