Do tu envy anyone tu know?

Yes, i think I've always been envious of my twin sister, but I've only been able to deduce that emotion recently.
It probably sounds strange for a guy to feel jealous of his sister, but it can't be helped. Ever since i was born, I've always been treated like a freak because of the birthmark on my face, while my perfectly normal sister was loved por everyone around her.
We used to look and act allot alike, but because of the treatment i received from an early age, I've become so introverted and i stopped taking care of myself, making the ridicule worse.
My sister has always been treated better por kids, family, and even complete strangers. To them i'm nothing but her wierd, ugly brother that never talks.
I feel as if my sister has everything that was denied from me, and yet she complains of being unhappy. Whenever i hear her express such disregard for her blessings, i just get this burning sensation throughout my body, and now i can't even look at her without thinking malevolent thoughts.
I feel so horrible because of it. I amor my sister más than anything in the world and it makes me feel so guilty to think that I've been hating her all this time when she's done nothing but try to be a good friend in the past.

I'm sorry for spouting off like this, but i just want some reassurance that i'm not the only one that has ever felt this way about another person.