What the fuck. My friend shared to me this doujin and I see this doujin is a cute one. I do like it but I understand why my friend is confused by the last page, which is "Why me, I don't even like it"
It was a mis-translation.
The original phrase in Japanese (origial raw) is...
I once told my big sis to "Fuck off" after the years I've been suffered, we don't contact each others since 2021 but I feel relieved after letting that off my chest. At least we don't argue each other anymore this way, just like my parents wish in the past.