Is it against the law the make a 9 year old child clean the toilet?

I'm going through a dispute with my sister about her making my 9 year old nephew clean the toilet. She makes him clean the entire bathroom, wash dishes, clean the living room and take out the trash everyday. On top of that, she has a boyfriend (who's not my nephew's father) who sit around and does zero house work. She allows him to beat on my nephew and not even 6 months ago, that same boyfriend choked my nephew and after he left because of the cops being called, she didn't press charges then allowed him to move back in. Now fast forward to now, that guy hits my nephew in his chest and tells my nephew that his dad don't care and love him. My nephew tells me this and I immediately get into a heated argument with my sister. Now she's not upset that her son is being abused, she's upset that her son said something about it. She immediately took her boyfriend's​ side over her own son and I want to call children and families services to get my nephew out of that house but I don't want him sent to foster care. My mother is sick and can't take of him and my girlfriend and I aren't married so I'm sure they won't allow me to get him. Even though if they asked him who do he want to live with, I know he'd say with me. I don't know what to do.