One commonway that an angry ex tries to align your child against you is to ankle-bite every thing you do in front of the child.
You showed up 5 minutes late to his soccer game, and your kid hears “See, if your Dad really gave a damn about you he’d be 5 minutes EARLY.”
Other examples include,
“Your mother usually calls you on Fridays, right? Well, what does that say about how much he loves you since he didn’t call you today? It is Friday, you know.”
“Your father didn’t take you to the movie today? He said he would last week, now, didn’t he? Would you say that’s lying if you tell somebody you’re going to do something, and you don’t do it?”
“See, if your mother loved you she would be so strict with going to bed at a certain time every night. See how easy-going I am? It’s because I love you so much.”
And on, and on, and on.
The fact is, in this parent’s eyes you can do nothing right. Every little slip-up, real or perceived, every single thing you do is under the microscope. Unfortunately for your kid, he or she has to hear this steady drum beat of negativity.
It’s another reason for you to simple stop– today– caring about what the other parent thinks of you. Trying with good efforts and nice gestures to get them to change their opinion of you, even slowly, rarely work.
Simply “do the right things” as a parent week in and week out, and keep a close relationship your kid. You can’t control what the ex says about you*, but you can control how you act, both around your ex and around your kid.
*But always be prepared to fight it in the courts, where you must hold these brainwashing parents accountable.