Here's my story and i really need advice on what should i do please !!

Well i love a girl from the first day i saw her ,in 9th grade (now im 12th grade) of course i liked a few girls in the past and stuff like that like everyone does right? but this was the only time i just felt this strange way they way i still feel i really really love her,she means everything to me i have the same feelings towards her as i have towards anyone in my family , it s really weird in 10th grade when i was fit not fatty like know i confessed to her but her response was negative she didnt wanna be with someone from our school (quite a lame excuse i m still frustrated about) cause later on like a month later she coupled with a guy from the same school ...she stayed with him for like 1 and a half year when i was still crazy and giving her gifts on special events ,but still couldnt really talk to her cause she knew i liked her and stuff and i still do but recently i found out she wasnt with that guy anymore and i started like workin out and suddenly she was with another guy short after leavin the first one them i felt like a bullet went through my heart , i felt so bad for a couple of days and now i still dont know what to do i cant talk to her i gave her a birthday present she thanked me but when i wrote her more she didnt respond so im really frustrated,depressed and sad in one way i tried to remove her from my head but it wasnt like i really wanted or i really could i like her and love her so much its very strange in that 9th grade it was the first time i liked someone so much and to be fair its not like everyone considers her a goddess or smth lke that for me she is one, everything about her is amazing to me but im really sad and without any hope in me sometimes i really think about things like why do u even live, why am i so unlucky, why does this happen to me and sometimes i just hate everything and everybody but i somehow dk how fake it so yeah so i dont really show it its really awfull... adding to this again she switched boyfriends after like a few month with that second guy thats what she tell me when i wanted to know her opinion again 2 days ago,dunno if its just an excuse to get rid of me or anything,i even told her she mean the everything to me but still nothing shown, but after this if i didnt have my bestfriend beside me i wouldve probably been no one i wouldnt ever smile or maybe even talk and still after these 2 big hits i still cant give up on her ,she is just something i cant describe for me ,sometimes i feel like i will go crazy if i do this more but i still cant stop thinking about her and have feelings for her ... :( i dont know how much i can go on like this i feel frustration,pain and i still love her and i just feel i could cry every time i think about her really and the fact that i cant have her or maybe i wont ever be with her really kills me this second hit was bigger cause i though maybe both of us got more mature maybe different tastes for each more about her of course but still no,i really feel so bad i am even afraid to look at her cause im feeling so much pain that i cant talk to her more likely she wont talk to me i feel like anything she did even responding to me sometimes she just does it so she doesnt show disrespect even when i liked her and she was single she never ever started a conversation with me i always did even though i was and still am really shy and didnt know what to talk about ,i dont think she ever answered something more than 10 words i guess so it looks like she didnt even wanna talk at all with me ,i dont know what to do really first i waited almost 2 years than i wait 6 more months to guess what get destroyed again ? i feel like i should give up on her anyone would say so right ? but i really cant ,i really tried while she was with that first guy i tried to be without any emotion and like try and find another girl but anytime i would like try and think about an other girl this same girs showed up in my head ,at the same time i would like to be with her but i wouldnt cause im not sure how much i need to wait or if i would ever be with her so i need a lot of help please !