I think I may have to call CPS on a hoarder's toddler... Advice?

My step-father's sister has a little boy, who is 3. She is in her mid 30s, is self employed and single. He is adorable, sweet and very shy. They live in a three bedroom 2500sq home on 10 acres of land, but she is a hoarder. She has a "business" selling items on eBay and I had no idea the extent of the hoarding until my mother and I came over to get a bicycle she said we could have.

There was garbage EVERYWHERE. Boxes of clothes, knickknacks, instruments, tools, broken electronics, plastic tubs filled with goodness knows what, hundreds of watches, clocks, mugs and dozens of empty beer bottles and cans. In the yard are about 7 visible cars on the land that are rusted without tires and lots of piles of things which are covered with tarps. It was truly shocking and extremely uncomfortable.

The boy doesn't have his own room, even though it is a 3 bedroom, because everywhere save for the living room is unlivable with garbage and junk. He has a fold-up crib in the living room next to the couch, where she sleeps. When we were there her power was cut off but she said she was getting it paid to have it back on, but my mom was skeptical because we know she isn't doing so well financially.

He comes to my mom and step dad's home a lot on the weekends and is always excited, speaks well, is potty trained but most times he's not very clean and his clothes are worn and too small. My mom is the only one who buys him new clothes, and she packs it up in his backpack for him when he goes back to my step-aunt.

When my step-aunt comes to pick him up he is terrified. He clings to my mom, holds her hand, looks up at her and says "Please, I stay here? I stay here? Please?" It breaks my mom's heart.

The mother seems to get great enjoyment in scaring him and think's it's hilarious. My mom said she had a hell of a time giving him a bath because he was so scared and crying. She asked the mother if he was burned, or what might have caused his fear and she laughed and told my mom "I told him he could get sucked down the drain haha, isn't that HYSTERICAL!? I can't believe he believes something so stupid!" She also made him fearful of cats and dogs telling him they want to eat him. My family has a kitten and he's scared to death of it.

My mom, step-dad and myself are the only ones concerned for his well being and my step-aunt's alcoholism. My step-dads parents just say she has a "sugar level problem" which is why she acts "strange". She has had fits of rage (a day after we took the bicycle she said we could have she called hysterical, calling us thieves and she needed it back and if we didn't she was calling the cops)

There are many more family members in the area, but all of them have no interest or are in complete denial of the situation. My mom has offered to pay for his day care while she "cleans up the place" but she was completely offended by the offer.

My step-father works 85% away on business out of the state and my mother just had back surgery and as much as they want to care for him, it's just not a real possibility. My step-dad is reluctant to get him into "the system" because we all know no other family member would step up, but as also know the odds of this situation improving is slim to none.

The last 6 months we've offered assistance, counseling, organizational tools etc but she is either in a drunken rage or sobbing uncontrollably at our "rudeness" and tells us it's just none of our business.

I'm afraid for this kid Reddit. Every time he comes over he is a little more dirty, a little more sad, a little more scared and he's always starving. He carries around a dirty Buzz Lightyear toy as his comfort and it just makes me so sad.

I would appreciate any words of advice, wisdom and experience.

TL:DR - My 3 year old nephew lives with his 30 year old hoarding mother, he is scared, dirty and hungry when he visits and no one else in the family gives a shit. Ideas?

EDIT I meant for this to go into Ask Reddit not AMA, apologies!