Pride and Prejudice Volume 3, Chapter 17
When Elizabeth tells Jane that she's engaged to Darcy, Jane at first doesn't believe her. Then Jane questions her to be sure that she is in love with him because she did dislike him a great deal when they first met. Elizabeth is nervous about telling her parents because even Jane was shocked and thought Elizabeth had lost her mind.
The next day, however, Darcy asks Mr. Bennet for permission to marry Elizabeth. Mr. Bennet grants it, but he warns Elizabeth in private that she must be sure that she respects Darcy or she will never be happy. Elizabeth explains how greatly her feelings for Darcy have changed, and once her father learns of what Darcy did for Lydia, he sees that Elizabeth is serious and wishes her joy.
Elizabeth tells her mother that evening and her mother is deeply apologetic for the way that's treated Darcy now that he's going to be her rich son-in-law. Everyone is happy for Elizabeth just as they are for Jane.