How do you help a person with problems?

Hi. I'm a 22 year old single mom. Ever since I was a kid, my family would compare me to my older siblings (we're 8: 2 brothers and 6 sisters) and would constantly tell me how I'm below their standards and how stupid I am. For years, I have carried those painful words they would tell me, and till now, they still keep on telling that to me. When I was in senior year in high school, I would always cut myself because of all the pain and humiliation I felt deep down. I couldn't tell anyone all the bottled-up anger, frustration, depression, sadness, and hurt I feel. I couldn't even muster to shed a single tear when they tell me how stupid, irresponsible, naive and weird I am. I tried committing suicide so many times I already lost count; even during my pregnancy. To add to all the pain, my family keeps on nit-picking on my daughter's dad, who left me when I told him I was carrying his child. It hurts so much. Recently, I found out my older sisters were talking behind my back, saying stuff that I thought they would never say to others. I don't know who I can trust anymore. I keep getting blamed for everything that goes wrong in our family and I had managed to deliberately hurt my own daughter. I would often shout and curse my daughter, slap her hard and tell her how much I hate her existence. I just can't seem to stop all the pain I feel inside. Please, tell me what I can do. I'm to afraid to talk to anyone since I don't know if I can trust them. I also want to know what's wrong with me.