I've read your posts and actually quite admire your ability to not only overcome mental and practical difficulties, enduring the horrible, but at the same time giving sensible advice to others here in the Forum. One thing you said that I particularly liked was
"Just remember your life is not over. You are SO young and you have so much in front of you. You've made it this far"
You yourself are around 21 I think , so your phrase fits you too.
By now the new years evening gathering will be over. It would have been a very horrible time for you and must have seemed endless sitting in the corner, surrounded by strangers and trapped as your father had the transport. I always avoided parties wiht strangers, still do.
You have had a bad year, living away from home, which might have sounded attractive and having a job, only to find your housemates were toxic and you had to leave your job to return home. Did your bond come back?
The nightmare of moving, especially with a bad foot and umpteen piratical difficulties is I'd imagine over except for unpacking the things you need.
From the sound of it living back at home is as bad as it was before -which prompted you to leave in the first place.
OK, so you have several things in front of you to overcome, all of which you have done before -and where you solutions have not worked out well then you will recognize the danger signals and it can be smoother this time.
Getting new medical support, a place to live and a job are all things you have proved you can do.
If you try to leave to one side the toxic nature of your current circumstances (no, not easy at all) then what do you think should be your first thing to get out the way?
I know if it was me I'd try for support, and that is partly medical and partly personal. with the medical it may help you with the self harm. I can understand why you try to cope that way, but it is so dangerous, though I'm not going to go on about that now. I do know that talking to the Suicide Call Back Service (as Sophie mentioned) can sometimes help a lot.
You may think different and go for job seeking as the main thing. It's your decision decided on as the person on the spot who knows what's best.
Is there anyone in your family or friends you can talk to who is on your side? They don't have to fix anything, just be a person to talk to who does not judge and simply cares?
Of course here you will always find understanding, care and fresh perspectives