I'm sorry you're in that place right now. 'Cause yeah, it's a pretty tiresome space to be in. I spent the first 35 years of my life angry. Got really freakin' old.
Tell me something, everlong: If you had this miraculous power to change yourself into somebody different, something different, what would it look like? You can't change somebody else - that's the unfortunately part of it - you can't change your dad's stupid choices or the clerk at the store or the guy down the street who hits his dog. BUT you can go inside your own head and heart with a big fat wrench and tweak yourself to feel whatever, do whatever, be whatever. You're all powerful and all knowing and you can make yourself into a completely different kind of person.
What would that non-angry, non-empty, non-lonely person look like? Sound like? Act like? Would you be smarter, more confident, you'd care more, you'd care less, what? Try writing it down, in detail, when you get the time. Write it first-person if you can. Talk about it as if you're already them. Doesn't have to be possible or even realistic. Just think it up, write it down.
That was the first tiny step on my agonizing journey to here. Sounds like things can't get much worse for you - why not give it a try.