Been thinking about suicide since 13

I am a coward. I should have killed myself when i first thought of it. Ironically, i am terrified of self harm. I came from a broken home. My parents were both hard workers, i never really went through financial hardships…. That i could recall but i was rather young when we were poor so maybe that is why. My father is an alcoholic, he always has been. He would constantly hit my mother in front of us and would cause a scene no matter where we were. He was only violent when he was drunk. I remember being 10 when things really started going sour; my mother was always “working” so my grand mother would take care of us, and i was during this time that my older brother raped me, i found out much later that he did the same to my sister. Around this time my father found out that my mother has been cheating on him for years probably. He lost it. I lost it also, i had so much respect for her and just like that our relationship was never the same. My sister became anorexic because my mom constantly teased her about her weight. During this time she considered suicide but i was never aware of her sadness. My dad saved her. My sister and mom never had a relationship. At the age of 13 my father moved out.my heart broke into pieces. At this point i wanted out. I wanted to die. I turned 14 and met someone older through afriend, it was her older brother. We started a relationship in secret. He saved my life. And now i have messed up by being unfaithful, the only thing i care about. I caused him pain. Now what reason do i have to live? I have none. I am 19 years old now, i still think about suicide.