I cut my arm because I was mad at the world and the relief was instant.
I hope that's not a habit for you. Why would you harm yourself over your anger?
It helped me to feel better. The pain from the cut stopped my sadness from overpowering me
You shouldn't harm yourself to feel better about things. Things can sometimes feel overwhelming, but if you resort to self violence then you may develop a habit of doing so moving forward. If you feel you can't cope emotionally, try seeking out professional help instead.
This helps me feel in control and it does help me in a way. It's better than punching a wall.
Cutting isn't a better option than punching a wall. You should make a mental health appointment for help with emotional issues. They can help you learn healthier coping skills.