Question

Overall in this book I have had many questions that have been answered. One though that I don't fully understand is how come Pip so ashamed that its the convict that's his benefactor in ch.39 pg. 318. I get that most of it is guilt and he wanted it to be Mrs. Havisham so he could marry Estalla, but still I expected him to be a little more grateful. Either I don't get this part or I'm looking for more than whats there. Message me an answer please.