The answer to your question can be found in chapters 14 and 15 of the novel. In chapter 14, Joe's wife has a bitter argument with Orlick which ends with Orlick being beaten in a fistfight with Joe. Towards the end of chapter 15, Pip comes home to find that Mrs. Joe has been attacked and that her head has been so seriously injured that she cannot speak. She seems severely mentally impaired. Pip strongly suspect Orlick of the assault, but there is no way to prove it because Mrs. Joe does not seem to blame Orlick for attacking her. Since Joe's wife has become an invalid, Biddy comes to live in the Gargary household to take care of her and to do all the housekeeping for the family. Mrs. Joe will eventually die and Joe and Biddy will get married and have a baby boy they name Pip.