Embarrassed to have my nephew hired on

Long story short, got my nephew a job. This job isn’t any regular job where people don’t care how you talk or any of that. This job has security, many cameras and cops around. It’s only been a month and my nephew has gotten into it with 3 different people, one including a girl smfh. My manager has talked to me twice about his attitude and gets offended right away when people tell him things. My nephew said he doesn’t mean to make me look bad but he’ll say something if someone gets in his way. I went above to get him into my job PLUS he never got an interview because I told my boss he was a good worker. So he got lucky he was automatically hired. It saddens me because I don’t think my nephew sees or appreciate my effort to help him get into here. One day I was off and he was going back and fourth with a supervisor saying “do better” next time smh and I had to message him and watch how he talks to them because he can get in trouble and all he did was laugh at my message. I said what’s funny I’m helping you so you don’t get in trouble and he was like I didn’t do anything. Whenever I give advice he won’t message me back anymore. He was happy to start and now he doesn’t talk to me. I’m afraid to tell my sister because they’re the type to make me the problem and they won’t talk to me anymore and I don’t want that. Even if I tell her she will go behind my back and tell my nephew I’m talking bad about him. 3 months ago my nephew lost his first child at birth and I was there for him and all of that. And decided to help him and get this job and he doesn’t appreciate anything I’ve done. Idk what to do or how to talk to him. It’s sad because I did my best to help him out and it’s embarrassing because my coworkers see how he is and for them to know that’s my nephew.