How to know is someone's family is abusing them and what to do....

I've made a couple post about a family moving across the sweet with 2 son. One my age (Sammy) and his older brother (Adam). Never mentioned our ages. I'm 18 along with Sammy and Adam is 25. Sammy asked me on a date. He's very shy and has a stutter. We had a good time. I'm kind of worried about thin though. I already knew his brother bullies him. His brother called him a cuck for opening the door for me, told him he will die a Virgin. Told ME I could get with a real man and that he(Adam) has a 14inch penis. Also felt the needs to continue to embarrass Sammy by telling me he still pees in his bed and poor Sammy looked humiliated. I just ended up telling him how my sister used to torment me. Our date ended on a happy note.... But I think there's more than just his brother being mean to him. I went by his house to ask if he wanted to catch a movie and heard screaming. His mom was yelling at him that he didn't do the dishes correctly. She was screaming does this look clean to you". I heard glass getting smashed on the ground and her saying "There. Now clean that up!" Idk what he was trying to say but he was stuttering and his dad yelled at him to talk normal stop talking retarded. I ended up going back to my house. I called him asking was he okay he sounded like he had been crying and he said "Yeah. I have to go". I'm not quite sure what to do... Normal people I guess would call cps but Sammy isn't a child.