ADVICE: My son father hates us. But acts like he love him when he see's him 4-5 times a year around others.

My sons father name is Larry Jvonne Davis, 24 year old Cancer black male who for some reason hates his 1 1/2 yr old son. He called child protective service on him. Quit his job and left me for another woman whom after 3 years, he is still with. He has taken things like his birth certificate, insurance card, and social security card and refuse to give them back. He has threatened me, along with his gf. I have bad dreams about him. I had become use to being a single parent, not by choice, as he did not want me to abort the child. He has professed his hatred to the both of us but continues to linger on ociation. I feel he is out to destroy me for placing him on child support that he is now behind $10,000 with no luck on getting help. He does not see his child. What can I do? Idont have much of voice as his family seem convinced by their only boy. Seems he contact me, for deceit, manipulation/vengence, not his son.But he acts like he love him to death in front of others. WHAT DO I DO?