How can I prove it? It’s a question you may not think to ask yourself until you’re standing in front of a judge, but unless your Ex makes it obvious to the court that they are a problem child, you’ll have a hard time proving their errant behavior if you don’t have documented proof.
What you can do. Keeping a calendar or simply writing down what happened at or near the time of the event is a good first step. Having family or friends observe your interactions with your Ex, then reviewing your calendar entries about these interactions is the best way to make your case. Keep a journal or a calendar to record your Ex’s bad behavior, and record it at or near the time it happens. These constitute what the court refers to as contemporaneous notes, and they carry greater weight with a judge.
But I hate keeping a journal. I get it. Writing everything down is a chore.
If that doesn’t work for you, try this. Let’s say your Ex is getting lax about picking up the kids when he or she is supposed to, or refusing to exercise their visitation, leaving you to wait endlessly because they don’t show up or call. Exchange the kids where you can buy a burger or soda, or fill up the gas tank. In doing this, you get a date/time stamped receipt while taking care of something you need to do anyway. Keep your receipts as proof that you really were at the exchange point, on time, and ready to pickup or drop off your child, and it was your Ex who showed up late (or not at all).
A picture is worth a thousand words, especially if it has a time stamp. If you’re having similar problems but the visitation exchanges take place at your home, just take a picture of them walking away from your Ex’s car. Provided you capture the image with a date and time stamp, you’ve made it very difficult for them to claim they were not late, or it was your fault, or whatever their usual excuse is. Even if they are on time, it will put your Ex on notice that you’re serious about sticking to the schedule, and able to prove it if they aren’t.
The point here is that you can’t wait until you’re standing in front of a judge to come up with the proof for your assertions. Figure out the easiest way for you to document your Ex’s bad behavior, whatever that might be. Dealing with a misbehaving Ex in difficult, but if you prepare, you can significantly improve your chances of things going your way in court.