And now Tongtong's mom will give advice to them..... I have a very bad feeling. I feel like it will make things even worse. Being the liberal woman that she is, she could hardly empathize with the problems of a responsible mother.

By the way, there seem to be several who disagree with my opinion that Tongtong's mother is a whore, disregarding the fact that she almost had her daughter abused by a degenerate. Shit, if he had really raped her the situation would have been much worse. I think the manga treats that situation too lightly.

Just in case you're being serious about your opinion or even remotely interested to listen to mine.

Tldr; TongTong's mom rules. Xiao Lu's mom drools.
Child abuse can happen even if the parents are in a loving mutually exclusive relationship.

Book Version:
Real talk, child abuse usually happens from the people you least expect it from. (i.e. uncle, dad, baby sitter, friend, etc.) You don't have have a "whore" mom to experience that. You're also making it sound like TongTong's mom TRIED to have her daughter raped. She stopped bringing her boyfriends home after that, didn't she?
Also don't think they are being too light about it, if they focused on it too much it would completely change the atmosphere of the story.

Tongtong's mom really is the better of the two mothers. It doesn't matter how hard someone works or sacrifice to make money for their children. At the end of the day if they don't bother to listen or try to spend time with their kids, what's the point? Who are they ACTUALLY thinking of? The parents who know AND love and accept their child/child can be comfortable and asks questions to their parents usually have the BEST relationship. (Tongtong's mom even waited years to get back into the dating game which extra brownie points for her imo single motherhood is hard)

Tongtong herself can be a bit of a degenerate, I guess considering she tried to blackmail her fellow classmate, but hey. All for the plot! These characters aren't real! Let's all just voice our opinions out for a bit and enjoy this manga, yeah? (Or not, I guess. Sometimes I read mangas I hate just to see how it ends, which it sounds like what you might be doing...) You do you!