I looked at the raws, the MC apologized and said he should have never called her that right after he said it. So he did know he was in the wrong and admitted it, and was sorry if he hurt her by saying it, and a little while after that they broke up because he said she deserved someone better than him.
The 2 of them had already talked about it before they even broke up.
She just didn't tell her brother all her business, so he assumed he just called her a slut and then dumped her and nothing else inbetween.
Her older brother is doing stuff on his own to get revenge that she never asked him to do, which makes the sister angry because they already talked about that, and resolved everything, and now her brother is sexually taking advantage of her ex boyfriend to defend her honor.
fuck you ...who're are u calling a slut ... u need a dick okay ,walk out of the closet and go get a dick and take ur misogynistic ass out of those poor girls lives ...u go girl ig if its revenge do it then