Why won't my estrange husband leave me and my son alone?

My estrange husband is born here in the states. He's forcing me to stay with him. I told him that I don't want nothing to do with him. He does not want nothing do to with me, that's fine but he does want nothing to do with my son. That's nuts! He made false statements against me to Child services and INS. Even though I have a green card, he still wants to put my son in the system and to have me deported. I spoke to the police and child service about this. They say, that he can go to prison for doing this! What should I do? I want this nutcase out of our lives and in prison for trying or attempt to hurt me and kidnap my son.