I found out recently that her mother hits her when she's stressed. The same visit, I learned that my brother would no longer have sex with her.

Pronouns, dude, pronouns...

On a more topical note

Ironically, if anyone in her life had to be suspected of sexual abuse... it should not be me, but him. I wouldn't dare make an accusation, and his parenting style is in itself enough that she's probably better off minus his smothering... but to be truthfully, 100% honest: it wouldn't be quite as surprising to me as I imagine that it might be to everyone else if I were someday to discover the worst.

...the only anti I've ever met offline is also the only person that I know for a fact has force-makeout'd a preteen girl.

They are seriously, universally, the sort of people who spout this shit because they, personally, keep getting told this, and think it's a universal thing.