I understand that, Carol, that's too hard for her to think about. And I although I had never thought about her history of PPD, that makes sense that it would make the situation worse.

But what I don't understand is how she could simply give up on getting her children back. (I understand that she's trying to fix the time machine sot they can go back, so in a sense that's not giving up. I respect that.) But she's still not trying EVERYTHING.

By execpting this reality as "default", she's trading in her mother and Lucy for her children. Once again, I can understand she doesn't want to "kill" her mother, Lucy, Dave all over again.
But where are the Christopher and Nate? They don't know. They can't even make the argument that they have parents, because they don't know enough about timetravel to know. And even if they do, they won't BE THE KIDS REAL PARENTS. Some one as perpective of Christopher, at least, should be able to tell the diffence. You could even make the arguement that they've abbandonded the kids by not trying everything.

And then, like I said before, how do they handle having anymore kids? They'll feel like the new children are replacements for Christopher and Nate.