My Nephew Wants To Come Live With Me

My nephew is 15 and is basically the parent to his five siblings. My brother and his wife make him home school so he can take care of the kids. And those kids are wild. They don't listen. They cuss at you. My brother and his wife do NOTHING because our parents pay all their bills. He is failing his online school because he's so busy cooking, cleaning, changing diapers, laundry, and so much more. Yesterday was his birthday. I went to give him a present and my sister in law said I should have bought ALL the kids presents. I stayed over for a bit and saw just how stressed my nephew was. The kids were cussing at me and he was trying to help the baby. His parents want to have more kids too! As I'm talking to my brother O hear a thud. My nephew fainted. I quickly got a damp towel and put it on his head and called 911. He spent the last of hos birthday at the hospital. Today he called me crying begging if he could live with me because he can't take it anymore. I called my brother to talk to him about it. My brother says "If he leaves, he better not EVER come back. He'll be dead to the family". I know I want him here but my best friend told me to make sure it's a good idea. Do you guys think it would be the right thing? Even if it means ruining the relationship with his family?