Is there any recourse? I’m sick of hearing my kid say “mom said.. <insert disgusting lie about me here>.”

In the divorce we “agreed” to not speak poorly of each other in front of kid. She’s directly telling them lies about me.

Here’s the thing: family law is fucked. I had a brutal experience with bias against men. There seems to be no recourse. What can I do? Directly confront her? No, because a) it’s not grey rock and she will LOVE to hear that she is getting under my skin and will therefore increase attacks; b) take some legal approach? No, because it will be expensive and I’m not trying to achieve anything other than get her to stop alienating me.

Seriously wtf do I do? Just ignore it? Hope it goes away? It’s been 2 years and she still shit talks about me to kids and friends and colleagues and family.