Perjury in dependency trial Justice System, Police, Courts

Ex has custody of my 9 yr. old son. He tried to commit suicide last year while son was alone in home with him. CPS took him to court for a dependency case. During the trial, the ex was asked of my whereabouts and how to contact me and he lied and told them he had no clue where I was at nor my contact info. The state sent my son to live with his paternal grandmother for 6 weeks while ex was bakeracted.
I live in GA and he lives in FL and I had no clue that this event even took place until the 2nd ex wife informed me after it was done with. I had even called my son during that time numorous times and nothing was mentioned. After being informed of what happened, I contacted CPS. They refused to remove my child out of the home and they stated that my son was doing well.
I paid the county courthouse for the record CD of that court event and I have the proof of his lies. I am taking ex back to court for a modification change of custody. The jurisdictional court is a separate jurisdiction from the court CPS took ex to. (another county 2 hours away)

My question is, How do I file a perjury charge? Which court do I file in? Our court jurisdiction that has handled all child custody/visitation cases or the court that held the trial of dependency?

Yes, I am going through this pro se...I understand I should have a lawyer but money is a big issue in my home.

Thanks for your answers