I believe in an adage: speak to kids about kid things, and adults about adult things. I personally would deal with this with your ex. At a drop off or pick up: "By the way, D said you said X. I would point out that my support is $3k and cover 70% of the kids expenses. I do not think it is fair for you to make comments about money to the kids. If you have a problem with anything address it directly with me and keep the kids out of the middle of it."

The kids know more than you imagine they do. These things have a way of being overheard.

That is just my opinion, but I do not think it would be wise to address with the kids.

M(53), W(54),D(19)
M-23, T-25 Bomb Drop - Dec.23, 2017
Ring and Piecing since March 2018