LIFE SUCKS

Feeling so lonely and insecured

Hi I'm a High School Student. My life to be honest is not that bad and I can not compare to other people's lives but personally I feel very lonely and insecured when I'm alone. I don't get along with people very well because while growing up there was no one really there for me.
My father left the family when I was the age of ten and only came back 7 years later leaving my mother to take care of my sister and I. She have to do double the work in order to keep us under a roof. While she work as a house attendant while having to babysit. My sister does not care much about the family thus went out hang out with other people, drinking and smoking. So during 5th grade and the rest of middle school I don't have time to make friends instead help my mother look after two kids that are around the age of 4 and 5. I have so much on my plates during those times. While preventing the kids from getting into trouble and helping them I also have to worry about school.
When high school comes I stop babysitting, but when I get home from school the whole place is empty and I felt so lonely, everyday either I turn on the computer and sit there or play my ps3 just to kill time. But everything is so boring. A lot of people say that I was lucky to have all these things, consoles, computers, ipod, iphone. But in fact I never find any joy using any of these things once maybe video games when I was younger. Then when my father suddenly come back to my life, he is not making it any better instead he is still as irresponsible as he is. Won't pay the utilities and always go out drinking. At night just start waking up the whole neighborhood having stupid argument with my sister. The worse is that he is trying to take charge of my life.
A lot of students in school discriminates me in school because of the lack of effort calling me stupid or retarded. The teachers are just being plain rude and disrespectful but picking on me and yell at me in front of the whole class because I rarely get any homework in when in fact even though I may not have bring in any homework, all the group projects was all done by me because I don't other people to fail because of me and the grade was always around the score of 95-100. They always think their duty is just to teach, they don't even care what's going on in my life that is causing me to do such poor work and thus always give me a grade near failing. They just group me in with the slackers when I never had once cut class unlike those people. I just have to take it in and try to let things go.
As miserable and lonely as my life can be I always kept it to myself. No one had ever ask about me ever. A lot of people like me because I always give things, help people, and put people before myself. People say that if I believe in any religion I will surely go to paradise or heaven. They can say how good I am all they want, they never knew how lonely, miserable, and insecured I am. I never found anyone that is actually there for me. It felt like my purpose in life is to be a tool for the people because once I helped them, they kept relying on me over and over again.