That's a very casual interaction after finding out your husband is a monster. Sure, you would've also have locked your sister up but there's a very real possibility that Fang Mu was the one who raped the captive man. (Or is she repressing the memory of the used condom on the ground?)
I don't think it's the real Fang Mu who is locked up. I think he might have something to do with Fang Yusheng and I think the homeless men were the ones using the condoms. Fang Mu is a whole new level of evil. 🤮🤮😡