I think your own values are coming through pretty clearly. Understandably, telling a parent they shouldnt have had kids is bound to strike a nerve. Having kids is great. Having kids is also the worst single thing you can do for the environment. Both can be true, and having kids definitely doesn't make someone bad.
However putting kids on a pedestal is silly. If we push our civilization above earths sustainable carrying capacity, we are fucked. In isolation having them is beautiful, in the aggregate it can be bad.
> Having kids is also the worst single thing you can do for the environment.
No, just no. You can't show that. You don't understand environmentalism. You're just a Malthusian. It's an assertion that human existence is incompatible with the environment, and that's a completely unacceptable proposition, because it defines "environmentalism" as "extinction."
Reducing the population by half will, at best, reduce emissions by half. That's not going to stop climate change. That's not climate action. That's not anything at all.
I really wish people with your attitude would study ecology, would study biology, would study the world. Life, human and not, all affects the ecosystem. All life depends on other life. We all interact, we all change the world. Life has fundamentally changed the geology of Earth in absolutely drastic ways! Life is impact. Defining environmental purity as the absence is an ideology bereft of life, and the nature of life.