Why must I undergo this pain?

This is my first post. I am 15, and always feel like I cannot escape the pain within my life. I have been raped, lost my grandmother, my father left me, I moved, I have been bullied since 5, very few friends, harassed, abandoned, misunderstood, and much more. I put myself before others more so than anything else, and I cannot bare to do otherwise. But I get hurt for doing such a thing. I support self defense, and I would do so if required, and sometimes I do want to, but I cannot think of myself doing such things to someone.

What did I do to deserve this? People seem to moan about the simple things in life, and I would love to be in their shoes, not worry about every single person, not always feel bad, the biggest issue being grades or dating. Not depression, harassment, bullying, reliving the worst memories over and over. I cant think of a day I have not remembered it. I do not cut, I do not want to worry people and have them spend their time dealing with the likes of me. A burden on their shoulders. I do not want to kill myself, because it might cause grief and I cannot bare that. Plus, I cannot do so with the thoughts of the after life, whatever it may be, my beliefs support that other beliefs may be true, I do not want to risk going somewhere to a pit where I have to relive it millions of times worst over and over and over. That truly would be worst than my situation, but I do not know what else to do, to get rid of the memory. I know I never will forget it, if I remember it now, if I am conscious now and I am aware of this whole situation and myself thinking about it, then I will never forget it. Because if I forget it in the future, then I can not look back and remember it like I am now. It would be mindless action. If you do not understand that, then sorry, I am also bad with my wording which surprisingly, makes it even worst with misinterpretations from others causing them to think something different of who I am. No one understands me. Not one bit. Life is hell itself.