I think it's a bit disturbing that you want to make every excuse for this "loving mother" for her actions, but whenever there are men whose acquaintances call "loving fathers, nice guys" who kill their kids everyone assumes the man must have been hiding his true nature.

If it had been the father who killed the kids, in the same circumstances, would you be so understanding? Would you still say "how can I judge another parent"?

Of course you can judge. There are some awful parents out there.

Unless this woman is like Andrea Yates and completely insane, she deserves no sympathy.