Our big age gap problem!

I have no idea where to post this, but I want to turn to you, parents of reddit, since my parents and I feel helpless!Maybe it's a condition, and I should be treated for it, maybe it's normal. I am a 19yr old female, and I have a brother, who is 12 years younger than me - he will be 8 this year.I was never ever a fan of babies, the thought of having a brother or a sister sickened me to my very stomach (I would love to have an older sibling though). And at 12 years old I was suddenly forced to have a brother. I was happy, at first. I loved to dress him up and cuddle him, but the second he learned to walk and talk, my hate grew. He is not a normal kid (he is healthy no worries, but it's how i see him), he is manipulative, he got a phone at the age of 5, he doesn't know how to act, he doesn't eat anything (which is why his skin is literally translucent and every vein is visible), he cries and screams at the smallest injuries (like a small paper cut or a scraped knee). But my dear mom is always here "he is so small'", "he is my little baby", "ofcourse he can eat sugar for every meal of the day". He has no comunicational skills, he is rude to others his age, he doesn't know how to act at all! He has no friends because of these very reasons.And me? I just hate his whole being, the catch is though, why do I feel bad about not playing games with him? Why do I feel bad for criticising hum all the time? Why is it such a dread to do literally anything with him? I mean he doesn't even know how to talk! He has a problem in saying "s, c, z,". His voice is so squeaky and he is such a cry baby. Please someone help me! I want to be a good big sister! But I hate it when my parents, at almost 20 years old, force me abd scream at me to spend time with him! Sincerely, I have no idea what to do with myself anymore, I just want to move away. What do I do? Any advice, any criticism will be appreciated, thank you. via /r/Parenting https://ift.tt/3ajH3Bq