By the sounds your brother wouldn't want that for you. Don't put the people who care about you through pain because your scared of pain yourself. If your not happy with your Mum go out and make a new family full of supportive people. I hope your brother doesn't die, try to make as many good memories with him while you can
You can fight this and you can feel better. Make sure you keep yourself safe for the meantime. If you feel like you're in immediate danger, make sure you call the emergency services or a suicide hotline.
You can fight this, and you can feel better. Your death would impact people beyond what you know.