Why do Sunni Muslims Hate Shia Muslims?

i'm a Shia muslim and i don't understand the hate, i mean, whenever i research something to do with Shia Islam i find loads of comments saying how we are misguided and not proper muslims. in my mosque we talked about Saqifah-where the people gathered to appoint a new leader even though the Prophet had... show more i'm a Shia muslim and i don't understand the hate, i mean, whenever i research something to do with Shia Islam i find loads of comments saying how we are misguided and not proper muslims.
in my mosque we talked about Saqifah-where the people gathered to appoint a new leader even though the Prophet had said that Imam Ali was the next leader-among other things, but we don't say bad stuff about Sunni's.
i also want to know why because i've been bullied about me being a Shia in school before, once in primary, and now that i'm in high school as well.
like , when i was in primary school, i told some girls i was a Shia and the next day when one of them was about to talk to me, her friend told her not to speak to me because i'm a Shia. and now, a girl in my Urdu class, told lots of girls that i'm a Shia, and some of them just said "so what?" but others stopped talking to me altogether. and once, a boy who was being silly said to me when i ignored him "don't be racist because i'm a Sunni and you're a Shia"
so basically i want to know why there is so much hate because now i dont like telling people my 'sect' because i get a lot of hostility.
PLEASE be nice in your answers! i'm only 14!
Thanks
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