The Chapter I think you are referring to is Chapter 49, where Pip has his last dramatic meeting with Miss Havisham. It is well worth the effort to compare this chapter with Chapter 44, where we see an unrepentant, proud Miss Havisham who denies any use and abuse of Pip through her actions. In Chapter 49, Miss Havisham is completely different - she is repentant and through her actions, speech and body language shows how she has reached a point of self-realisation (much like Pip) where she has realised what she has done:

"Oh!" she cried despairingly, "What have I done! What have I done!"

Pip, at this stage of the novel, has changed too - through his own trials and pain he is able to empathise with Miss Havisham's sense of regret and self-realisation, and therefore is able to offer forgiveness freely, commenting that he would have fallen in love with Estella without her help. This chapter therefore represents a continuation of his moral regeneration through his ability to forgive Miss Havisham.