First of all: Oof. I feel you. Sounds rough.
It sounds like you need some joy in your life. I can think of three main areas where you might be able to start to have more of that in your life. First and foremost, you would benefit from a social life - as it seems that you are aware. I don't know enough about you to know what the obstacles preventing you from finding and growing a social life are, but that seems pretty important to figure out. If you've got free time, you should be able to start to cultivate a social life.
Second, a hobby that gives a bit more of a sense of accomplishment. I'm artistically oriented, so I tend to think of arts and crafts, but really anything where you're developing a skill would work. (I know that playing video games is a skill too, but you know what I mean.) A second advantage to a new hobby is that it is an opportunity to engage with a new community of people and in that way start to look for new friends.
Third, beauty. This can be a challenge if you're struggling financially. And I understand the house you live in is gross in ways that you don't control, but creating a sanctuary for yourself would be good. If you can't change your space, maybe you can spend more time with your eyes closed listening to immersive, beautiful music.
Of course this is all a bit of a challenge to accomplish. It involves creating new habits, and if you're starting from a place of depression it can be hard to find the motivation to power those changes. But making those changes is the only way your life is going to improve. Ideally, you would come up with a vision for how you ideally want to spend your time and then start with small changes that you can mostly sustain, building up to the goal.
I'd be happy to talk with you further if you like. It seems like you may need some help figuring how to overcome your challenges to developing a social life. I'm also available as a kind of accountability partner to help keep you on track with implementing changes that you decide on. I'm also available if you just want to talk a bit more.
Good luck.
From my perspective, they need some good therapy, or something that functions as therapy under a different guise. Medications can help manage Sx, but unless they learn how to examine and work with their mind, they're basically going to spend their life feeling out of control and at the mercy of some combination of impulses/neuro-chemisty/exo-chemistry. It doesn't have to be called "therapy." But they need someone who can teach them how to work with the mind's deeper patterns and forces (and honestly, most therapists can't do this either). The only other place I know where this is done is in a variety of spiritual traditions.
That combination of Sx also basically screams childhood trauma of some kind. Basically they need to learn how to bring healing to the wounded place in themselves is, in a hidden way, driving most of their troublesome behaviors. I can't explain how to do that over text, but it is certainly do-able.
They might have to hunt around for the right techniques or teachers, but if they pursue it with dedication, it is attainable.