I’m trying to remember. The sister isn’t blood related at all right? Her mom got remarried and the sister came from her stepdad’s previous marriage? Something’s not checking out. Unless her mom didn’t actually want her and was forced into a marriage with her dad that isn’t in the picture and somehow, looking at her, reminds the mom about the relationship she hated? Maybe her grandmother forced her mom into an arranged marriage? Still, that doesn’t just make it okay to take your anger and frustration out on your own child. Bro, idk, but DAMN. The mom is literally treating her like she’s worse than a parasite.