This is because she's basically giving a woman who has no real emotional support and no way to explain what went wrong that isn't staring her in the mirror the refugee in the war zone speech. When she has time to think things through, she'll realize that while she has another hard slog ahead of her and will have to earn another happy ending for her loved ones, she does admit that maybe she got ahead of herself. In the immediate future, she'll think of Elly as being a well-meaning clod who unintentionally said something inappropriate and hurtful because she thought she was helping. Once Elly ditches her because she stupidly misreads things, she'll have a good chuckle at her expense imagining what would have happened had what happened to Leah happened to Lizzie.
As I write this, I do so in the knowledge that as they sip margaritas at Cabo, Annie is telling Steve "If you think Elly would have blamed herself if one of her kids had twelve fingers, you are daydreaming in Technicolor! I know that crazy rhymes-with-witch better than you do, pal! She'd have just stood around screaming about the ungrateful, selfish brat who decided to be born with extra fingers because it loves chaos and hates her soooo much, she has to go broke buying custom gloves forever and ever."