I'm sorry you're going through this. People can carry only so much suffering and pain and yours is too much. Have you talked to your brother about how you feel? I know it's awkward since he's your brother but if you want him to understand, you need to tell him first. Acknowledge that both of you suffered a lot from your parents. Your brother copes by taking it out on you and you're to the point of being suicidal. If he bullied you so much, why does he get scared when you kill yourself? Do you think it's out of genuine concern or he's just acting because he won't have anyone to bully anymore? You know your brother more than I do so I don't know. Has your brother ever told you why he abuses you?
Deep down, I know both of you wish and deserve a stable home life. Please talk about your feelings and his. Both of you might cry a lot because it's really emotional to talk about these things with your siblings. Have you ever told your brother "I love you" heart to heart and meant it? I know both of you are tired and don't want to go on anymore and are at the end of your rope. I can understand if you want to fall and not hold on any longer. But if you have just a little bit of willpower left, try having a heart-to-heart talk to your brother about your family, how you feel about him, how much it hurts when he abuses you, and what you wish for. By wishing for, I don't mean suicide, I mean wishing for a happier family, love, a better relationship with your brother, and so on. Let him speak and cry too. If he interrupts you, try to be the bigger person and not do it back. Listen to him intently like you'd want him for you. I'm sorry you're going through so much and your support outlets are few but I wish you the peace, happiness, and stability you deserve.
Thank you