How do I stop my ex from spreading malicious rumours about me?

I spent many years with a cheater and even had a child by him. I finally muster up enough courage to leave him for good after he almost cost me my life. Recently, after a long period of him out of my life, we had a talk and I set some boundaries and conditions and I allowed him to come over to see our child again, he has crossed the boundaries by attempting to sleep with me. While newly married to one of the women he was cheating on me with. After discovering his treachery, I called him up on it, and put an end to him come to my house on the pretence of seeing our child. He has since retaliated by calling my family and friends and tells them several lies about me- the reason he is not with me is because I am crazy, that I am a liar, that I cheated on him and that our child is not his. It has gotten worse when he found out that I am dating someone else. I have gone as far as seeking legal advice to see about obtaining legal and physical custody of our child together because he claims that I am harassing him after I asked him to do something for the child. He has not seen the child in a year and shows no interest in seen the child. He has refused to give me legal custody of the child amicably so now, I am having to go through the courts with him. He flat out told me that no one is going to make him spend time with a child he does not want to. I am at my wits end, Help please!

U got what u want him out ur life so whats the problem u want to control him u could have let him seen the child anywhere but ur house the fact is u want him call him and tell him to come over and do what u got to do and he ll stop talking about u and he ll do the baby right u making him rebell against u and the baby he might have cheated on u but u left him right