Am I wrong for not saving coparent anymore.

50/50 custody.

My ex always makes promises to his kids and doesn’t follow through the majority of the time. Hell promise something and even tell me THEN turns around and says he never said that or that that’s not what he meant… or my favorite there were contingencies to said promise. He gets pissed. Thus making the kids/ me upset. Gaslights the shit out of everyone.

I usually save him by following through with HIS promises so the kids won’t be upset. I’m not doing this anymore. The kids are old enough and their dad can dig a hole for himself. His kids will soon learn they can’t trust him. Every time I save him it resets and the kids trust again.

Am I wrong? This is so hard for me. I hate seeing my kids cry and be upset. What can I do?

Edit for more context: he tells them if they do something for him or get good grades that they’ll get X thing. They hold up their end and he does not.