Defamation for custody purposes

[Mtkuna]

My wifes ex-husband recently was granted an ex-parte in family court that prevents me from being around my step children. He stated in his request for the ex-parte that I pose a threat to the children and that they are afraid of me along with a bunch of other lies that can be proven false. The children testified in court that I have never hurt them and that they are not afraid of me. We are still waiting after 7 months for a full hearing. My wifes ex-husband made up these stories because he feels threatened by the enormous amount of attention his children give me and that he also thinks I took his wife away. Can I sue him for Defamation of Character?