I've lived with crippling depression and anxiety, and I can tell you that you were right when you said this:

i can tell that i am deteriorating mentally and physically staying like this.

And I know that with how you're feeling right now, it can seem like the most logical thing to stay like this until you feel better before crawling your way out of that deep hole again. It won't work like that. Start working on your own (mental and physical) health again. Build up your life again.

Start really small, take small steps forward. You mentioned living in filth: you could start with that. Clean up a bit each day, until you're living better again. I know it sounds incredibly dumb and too simple to work, but it helped me get out of a very dark place.

And like someone else already mentioned: visit a doctor. A decent one. I don't know where you live, but in some places healthcare for mental illness is at least partly supported. Maybe look into that first.

If that's really not an option, these days there are other resources. Organizations you could call, or even chat with online.

Finally, I'll leave you with this quote that gave me some insight, so who knows, maybe it'll help you too:

Change your thinking: you don’t have to solve your entire life all at once. Instead, try to think about adding more good things to your life. Add them one by one. And slowly, the amount of good things will grow.