...vanity (and Mary is more likely to spout a truism than something wrong), then Lizzy's reaction to Darcy's "not tolerable" rudeness is umbrage about what others (or another) thought of her, not what she felt about herself. That is precisely why she can tell her friends, but that does not mean her vanity was not hurt by hearing Darcy's opinion, nor does it excuse Darcy's behavior.

I do think Lizzy allowed Darcy's actions towards her at the assembly to influence her future behavior towards him. Do I think Lizzy was being superficial? Superficial is not necessarily the word I would use, but I do believe Lizzy reacted in a manner atypically in error for one of her intelligence, poise and wit. She was not at her best in her reaction here (or her perpetuating her dislike) any more than Darcy was.