Stop worrying about losing your children. IF you keep your side of the street clean, a judge isn’t going to hand three kids to a man who won’t keep a job and has no means of taking care of them. If you are the one who takes them to the doctor, oversees their studies, spends your time with them, they will keep the kids with the stable parent.
As for your mom’s advice, she is mistaken. You aren’t telling him anything to give away a game plan. In many places you are not allowed to record conversations unless BOTH people know they are being recorded. Otherwise it is a crime. You are telling him that so he will leave you alone and stop the verbal abuse on the phone. Hold the recorder up to the mouthpiece. Maybe just the threat of that will stop him from annoying you. THAT is really what you want.
Always presume when you talk to him that you are being recorded. That will control what you say. Why you even would want to talk to him is beyond me. Send him emails with just the facts about the kids. And have his lawyer write your lawyer. If he has to pay his lawyer to communicate, that might make him stop.
As for his claims of starving to death because of you, just smile to your kids and say “I’m sure he has a sandwich in that big ol’ condo of his somewhere. He looks healthy to me.”
They’ll eventually figure out he loves money more than he loves them. You can’t stop them from rewriting history. And when they are teens they do that. Just do what you have to do so you know you did the right thing. Forget friends who have issues with their own parents. You know what the facts are in your case. You are providing your children with an extended family because they need that. You cannot be expected to follow your ex around the country every time he moves. Stop justifying your actions to people who aren’t paying your bills.
The courts are used to his kind. They are a dime a dozen. He has a long record of evading responsibility. Stop worrying about that. Your daughter will grow up and see him through the eyes of a woman. Eventually he will disappoint her the way he disappointed everyone else who depended on him. You dont’ need to say anything. You will have all the responsibility and hard work caring for the kids. Do it for love not recognition. He will reap what he sows. But it will take a while. When your daughter makes comments, just ask her “What do you see?” Make her examine the situation in her own mind, evaluate what she sees, not what she is told, and come to her own conclusions. That is a useful life skill.