I can totally understand what you're saying, as an adult I have been there myself. Until it got too horrible to bear. But I was a lot younger then.
Perhaps if you didn't look so far ahead. Your trying to make the jump from a-z without looking at the steps in between.
Right now all you see is being in or being out. What if you could find a middle ground.
Maybe starting with a part-time job in something you enjoy. Something that gives you your own finances, independence and empowers you somewhat.

Give yourself time, you might find that those changes are enough to make life a little more bearable for the moment, see how you settle in. Don't beat yourself up for being afraid, it's a big undertaking. I try and make it smaller.
Don't say, I need a job so I can get out. Just that you want something that is yours.
In the end only you know what you can manage, I do wish you and yours all the best though.