Does anyone have a summary for chapter 15 of the book ‘Summer of the Mariposas’?

Summary of Chapter 15 of the book "Summer of Moths"

In chapter 15 the girls discover more about their family and their origins, because they managed to find their grandmother, who can talk to them and answer most of the curiosities they presented. Although finding the grandmother is a time of joy for the girls, it is also a time of concern. That's because Pita was bitten by a chupacabra and is not doing well, and may even die. However, the girls' grandmother knows a way to cure a person bitten by chupacabra, the process is slow, but it seems effective and it is a hope for Pita.

While Pita is being treated, the girls' grandmother talks about their parents. She talks about how their father was a difficult, selfish, abusive and authoritarian man. She also says that their father abandoned and wants to divorce their mother who may be very upset about it. Upon hearing the grandmother, the girls are worried about the mother and decide to return home to support her. At the time of leaving, with Pita already recovered, the grandmother says goodbye to them and tells Pita that she is very proud that she defended the sisters with such courage.

she was trying to use   reliable narrator.