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Part 2!

A common story is that several people started throwing insults and/or rocks at the carriage they thought contained his French-born mistress Louise de Kérouaille, calling her the "Catholic whore" until Nell Gwyn leaned out the window and noted with a smile:"Good people, you are mistaken; I am the Protestant whore."

Mrs Darcy is probably the older sister due to Mr Darcy being older than Anne de Bourgh.

As both sisters have only three children between them, and Mr Darcy and Miss Darcy have a massive age gap, AND Miss de Bourgh is described as sickly, there's probably genetic fertility issues. Personally I headcanon Miss de Bourgh as having endometriosis due to how pale and tired she is; period pain could have her bedridden each month and anaemia would do the rest. If Mrs Darcy had it as well it could have made it very difficult for her to fall pregnant. Given the ten year age gap I find it unlikely that she's had a child every two years and every single one until Miss Darcy came along just happened to die. I think it's more likely a combination of difficulty conceiving and deaths in infancy.

Given that both Mr Darcy and Lady Catherine look down on people, it's likely Mrs Darcy did as well. However even Lady Catherine appeared to be at least partially motivated by being genuinely well meaning, even if she was likely primarily motivated by egotism. Given that Mr Darcy snaps out of it with a good talking to and is known for his kindness and generosity, Mrs Darcy was probably closer to his end of the scale despite probably being a bit snotty about it. (Mr Darcy Sr may have influenced her to be this way, or Lord de Bourgh may have influenced his wife to be particularly awful.)

Given how loyal Mr Darcy is to his sister Mrs Darcy was probably very loving towards her children. If Mr Darcy lost a lot of siblings in infancy it may also go towards explaining how close the siblings are and how sheltered Miss Darcy is; she was likely very protected.

Given that Mrs Darcy's sister is Like That she probably had some social judo skills, or was otherwise a bit of a pushover. I wouldn't be surprised if she never actually agreed to Mr Darcy being betrothed to Miss de Bourgh and Lady Catherine just interpreted a "maybe" as a "yes". I always thought it odd how loyal Mr Darcy is towards his family but doesn't think twice of discarding Miss de Bourgh, but if his mother didn't actually explicitly approve an engagement that would explain it.