Who is Mrs. Joe Gargery?

Mrs. Joe Gargery is Pip's older sister and only surviving kin. From the beginning, she is an unpleasant woman who abuses both her husband and her brother. She comes off as bitter about her station in life. It is clear her marriage came about due to need for financial security rather than love. She is enthusiastic about corporeal punishment, often subjecting poor Pip to her angry abuses when she believes he's misbehaved.
What keeps Mrs. Joe from being totally evil is how hard she's had things. Her parents are dead and left her with a baby brother to take care of even though they were all very poor. However, this does not excuse her behavior, and her lack of love towards her family is part of why Pip grows up so insecure.

Mrs. Joe Gargery is Pip's older sister in Great Expectations. Also called "Mrs. Joe," she raises Pip after his parents die. While Joe is a sympathetic and caring man, Mrs. Joe is an abusive person who hits Pip and treats him with contempt. She often beats Pip with her cane (called "Tickler"), and she is generally bitter about her lot in life, as she suffered the loss of her parents and five brothers at a young age.
Joe bears her abuse of him with good cheer, and he does his best to protect Pip. Mrs. Joe is not savvy about the ways of the world, and she believes the outrageous lies that Pip tells her about Miss Havisham's house. Later, Mrs. Joe is attacked by Orlick, who works with Joe in his blacksmith shop, and she is maimed.

Pip's sister, who raised him "by hand," is immediately introduced in Chapter 2 as a termagant, explosive, shrewish woman who abuses poor Pip verbally and physically. Dickens tries to make every chapter dramatic, and in order to have drama there must be conflict. Creating such a contentious, chronically dissatisfied character as Mrs. Joe assured Dickens that he could invent plenty of conflict up until the time she is nearly killed by a mysterious intruder. Some sort of conflict develops every time Mrs. Joe appears in the book. She has conflicts with Pip, Orlick, and her husband. It turns out that her quarrels with Orlick motivated that ill-tempered, vindictive man to try to murder her. (Orlick himself may have been created because such a man was bound to create scenes of conflict to enliven some of the chapters.) Dickens evidently planned to have Mrs. Joe die off somewhere in the novel so that the kindly, long-suffering blacksmith would be able to marry Biddy and finally have some well-deserved peace, love, and contentment in his life. There is a sharp contrast between Mrs. Joe and Biddy, which makes the modest, patient Biddy seem all the more charming. She is, in fact, one of the most likable characters in the book. It might be said that Pip's sister brings her own death upon herself with her bad temper. She makes Orlick hate her so much that he tries to kill her. She is permanently incapacitated by the assault and eventually dies as a result of the injuries received. Her condition as an invalid explains the need for Biddy to come and live in the Gargery household, and this is what ultimately leads to Joe and Biddy falling in love and getting married.