Does Estella change at the end of the novel and does the change in her seem real?
To start, here is the eNotes analysis of this character:
Adopted by Miss Havisham at the age of "two or three," Estella is taught from then on to reject all who love her. This is Miss Havisham's vengeance in reaction to her romantic disappointment by Arthur. About the same age as Pip, Estella acts much older than he does and snubs or insults him more often than merely ignoring his attempts at friendship or love. In this, she is quite honest with Pip, for she has been raised to be cruel, to tolerate or to brush off love, and to reject it later in order to watch the man suffer. Miss Havisham's success in raising a cold-hearted beauty is too much for her, however, for Estella can feel no love for the old woman either. Thus, Estella cannot help but to refuse to give Pip any hope of marriage whenever he confesses his love. Instead, she tells him that she will ruin the man she does marry—and why not, when she cares for no one? When she becomes engaged to Bentley Drummle, Pip cannot talk her out of marrying such a brutal man. In the novel's revised ending, when Estella meets Pip years later she has had a daughter (also named Estella) by Drummle, who has died. Estella has survived, but she has been "bent and broken" by the doomed marriage. She has never found out who her biological parents were because Miss Havisham has led her to assume that they were dead. More tragically, Estella has never learned to care about anyone's happiness, not even her own.
Through this analysis, Estella has never overcome the disservice done to her as a child. She has never changed.
However, there is another way to view the ending. Estella, through her harsh experiences, has actually learned to be humble. She says as much. She says to Pip in the end, "I have been bent and broken, but—I hope—into a better shape." She believes herself improved. She has passed through the homely blacksmith's fire, just as Pip has, and she no longer possesses the same sort of lofty removal from things as she had in her reflected, starry light. Because Dickens makes this change so slight, it is believable. She has not learned to love, but she has learned to regret that she does not.