Hi I am new here on the forums but I have a really big issue that is confusing and complicated and really need some advice.

Basically I have very strong feeling for a girl I don't know and have done for about 2 maybe 3 years. It started as a little crush but the became more than that. I have recently told this girl I like her and she said "oh ok you don't even know me so leave me alone but thanks and bye" she then blocked me but as she said leave me alone I have never approached her or talked to her . I am having massive trouble with getting over her. I have done tons of research about this and there is no way of avoiding her as she is my friends cousin (this girl I have never talked to) the reason I like her so much is because lots of people told me that she is a very nice girl and other nice things. But she is also very mean as she says mean things about me to others. I am just stumped and don't know how to deal with this on my own. This situation is a lot more complicated but this is the basics of the situation.

This girl lived in my street and she thinks I'm a creep even though I have not done anything or said anything illegal or creepy to do with her.

I would really appreciate any advice you give so thanks so much.