Hi Ayeba,
I am sorry for you going through so much right now. Please bear in mind that better times will come, even if it doesn't look like that at all at the moment.
If you feel overwhelmed and are really angry, and your urge to self-harm comes, try to pour cold water from a tap or shower over your arms and body parts where you would usually hurt yourself.
Maybe listening to certain music can help you too, i know some people who listen to Heavy Metal when they're angry and it helps them calm down.
In general, try to talk to someone about your problems, maybe a close friend or a therapist, there are also phone hotlines and online chats.
I wish you better times and always remember: you are loved and you are a great person!