These are some questions, which you don't have to post answers to if you don't want to, but to think about and maybe help you work towards a solution.
What's causing you to be miserable in life? Is it something you can change?
When do you have rare moments of happiness? Is it possible to prolong the things that make you happy? Are there more things you could be doing (hobbies etc ) that also would make you happy?
There are apps, etc that you can vent on, even the Dear You thread on this forum. When you start to feel angry, would it be possible to walk away from the situation and use those things to vent?
Similarly, when you get angry , could you do something like count to 10, or pinch your wrists, or something to help you calm down?
Is there someone really close that you can confide anything to?
Hope this helps.