First off, I would like to say I'm sorry. I'm sorry that you had to grow up alone. Whether that was physically or mentally, it was not fair by any means. I feel your pain and I wish I could take it away. I have been there too many times. I grew up alone and afraid of the world because I had to fend for myself.
Some of you have to do this while having other siblings. You not only have to take care of yourself, but others, as well — and that is one of the hardest things to fathom. Your parents miss the most important things in life such as your first win in a soccer or volleyball game, or the time when your school had "bring your parent to school" day, and they didn't show up because they were working.
These are one of the hardest things in life. But let me tell you something... don't let these events turn you into a bitter person. Don't hold on to the hurt and anger for them not showing up. Instead, become that person who reaches out to others who don't have someone there for them and be that role model you always wanted or that parent you always wanted. You never know, you might make a huge impact in the life of another.