Nettie tries again to convince Corrine, attempting to remind Corrine of the time she and Olivia met Celie in the cloth store back in Georgia. Nettie brings out a quilt made with the material Corrine purchased that day, while Celie was in the store, in an attempt to jar Corrine's memory.
One might assume that this event only had importance for Celie, since Celie experienced the shock of seeing her child, whom she believed dead, out in the world. But as is evident below, the event was also deeply important for Corrine—so important, she had to suppress it.
Corrine suddenly announces that, on that day, she was afraid Celie was the real mother to Olivia, and that Celie would want to take Olivia back. Thus Corrine reveals that she has in fact known about Olivia's possible biological relation to Celie, and has had suspicions about her children's parentage, for many years. In the middle of the night, Corrine tells Samuel that, finally, she believes Celie is the children's mother. Samuel is relieved to hear this. But Corrine is very ill, and dies upon affirming this belief, with Samuel by her side.
As a component of Christian belief, it is important to die having repented one's sins—thus the value placed on deathbed confessions and conversions. Although Corrine has spent a great many years silently, and then openly, resenting Nettie, her desire for forgiveness at the end of her life means that Corrine will, according to her beliefs, go into the afterlife a repentant, or saved, individual.