What should I do about this family abuse?

Ok, so I was at a graduation party earlier today. There was a little boy there named Justin, and he's 4 years old. It turns out his father was one of my old next door neighbors and my parents know him fairly well. He came downstairs while I was playing Call of Duty and was complaining about his feet. I took a look and they were somewhat bruised up because he was running around outside without his sandals. Anyways, my Aunt came down and took a look and ended up washing them off with a rag while I put A+D on them and put a band-aid over the cuts. However, while we were doing so he was talking to us. I can't exactly remember how the entire conversation went but he said that his brother hit him. My aunt said that he needed to tell his parents, and startling enough he said, "My Daddy hits my Mommy!" I had absolutely no idea how to respond. He also said, "Mommy said my Daddy's always drunk." It turns out maybe his wife wasn't at the party for a reason. Earlier in the evening I was talking to his father, and he was completely drunk because he had a horrible lisp throughout the entire conversation. He actually drove his two boys home practically, if not, drunk. My aunt ended up making a huge scene claiming he was a horrible parent if he actually drove them home while intoxicated. I know that boy isn't being raised properly through his actions. What should I do about the whole abuse towards his wife? Plus, his brotherly abuse. I feel so bad for the kid! I don't even know if I should get involved. Any advice is appreciated!