My family lets the house be filthy and covered in mold :[

OK! A scary title, but it is true!

For some backstory on my living situation, I live with my three family members: my brother, mother, and grandma. My grandma and mother do not work and get disability checks every month, so my brother and I are the only people who work. My mom uses her money to get groceries for the household, and everyone else helps out on rent. It's really a choppy system, especially since I only work a part-time job [the job market sucks where I live...], and my brother always has more money than both me and my grandma, yet he bleeds us dry for rent every month...

Now, I'm not here to complain about being able to live in a home with provided food and water, BUT... It's borderline unlivable in here. 

My room is carefully cleaned by me, never having mold or rotting mess. And while I do get bad depressive episodes, I always make sure that after I get out of them, my messes are cleaned up well!! So...why are my family so lazy as to never clean their messes outside my room?

There is mold in our kitchen, rot in our fridge, almost every single perishable food is openly rotting. There are cockroaches in the walls that come out at night and skitter around. There are overflowing and crusted dishes in the sink and around the sink. The bathroom is always left a mess, scum and filthy everywhere. No one has the will to even sweep the place, and we have a very fluffy dog!...but me. I am always the only one to clean and cook and do anything worthwhile..

It gets really frustrating. I know that everyone in this house is perfectly able-bodied to clean, and there are no outstanding mental disorders as a reason as to why they don't do anything in the house, they are simply... too lazy. Maybe they know it will be cleaned by me in time, I'm not sure. But I'm so tired of having to clean after these people!! If everyone did basic cleanliness habits, this would happen! And it's not just in the common places of the house either! Their rooms are disgusting as well, they just...don't do anything..?

I have been brainstorming recently on ways to fix this problem, it's in my nature to find solutions to issues. While I do not believe that my family will ever change [since there is a LONG history of them not doing things they swear or promise], I have stewed over trying to get a mini fridge!! If the kitchen fridge is a moldy and filthy box of horrors [openly rotting fruits, veggies, and leftovers!], it would be easy to curate a small fridge in my room! It would be a bit expensive, but it's a goal to look forward to and save for! But...other than that, I don't really know what else to do..? Any suggestions?