Do not look at the mess and think about how much work it will take to clear it all out, that’s just going to overwhelm you and make you frustrated, so focus on your living space, wherever you sleep. Do some massive cleanout of your immediate area. Then the kitchen and bathroom(s) that you use specifically. Focus on yourself first.

As they say, always put on your own oxygen mask before helping anyone with theirs.

That’s it, just focus on having a clean room and hygienic bathroom and food-prep areas. You will face constant setbacks and every time you clear a countertop, there will be a new sack of clutter and bullshit placed there the next day. Learn to manage your frustrations and keep to the plan while you work on getting your own life together enough that you can move out and get therapy. You will need therapy.

If having a couple small clean areas inspires your family to do more, great. Just don’t expect it. Hoarding is a mental health problem that needs serious treatment and some level of self-awareness by the hoarder that they have a problem, so don’t expect to fix it, just try to carve yourself a path out.