How to handle the verbally abusive Father of my children - Law?

I live in NJ. I am divorcing my husband of 6 years. He is a verbally abusive, pathological liar who does nothing but try an ruin my life for leaving him. He is upset that I wont take his crap anymore. He cheated on me for 4 years, and had a child with another woman while we were married. We have two small children together. Now that I have left him, he has become way worse. We cant have a conversation about the kids without him calling me fatty, stupid, the c word, and a bunch of other insults. He has even gon as far as making up child abuse claims. For example, when I drop the kids off to him on switch days...after he gets them and leaves, I will get a text from him asking why our son has a black eye. Which he doesnt have! But he is trying to tarnish me...when he is the bad guy. I have now begun taking pictures of my kids everytime they are given to him, to prove that they are ok. Thats the kind of guy he is. What can I do to stop this from happening, while keeping the channels of communication open for the sake of our children? How can I force him to be civil when speaking to me? Are there any third party intermediaries that cant be between us? I can be the first person to have this issue...there has to be an answer. Thanks...