I like and am possibly in love ith my best friend?

i think im in love with my best friend.at first when we became friends like 2 years ago i just thought of her as a friend but around 6 or 7 months ago i developed feelings for her.i have had them since them and they are not go ing away.i think about her in class i dream about her when i sleep and im sometimes depressed and just seeing her brightens up my day and i always cant stop looking at herr beautiful blue eyes.We talk nonstop over text and facebook.she says she loves me and im the sweetest guy ever.when we text if u put a heart in a text she puts 2, if i put 3 hearts she puts 4.But i knows shedoesn'tt like me more than a friend i have asked her out 3 times and she has said no really sweet but idon't't want to be with you like that.and she is currently dating a guy who she has dated before and what she doesn't know is that he dumped her for another girl and this thadidn'tnt work out for him hes coming back to her and i cant tell her that because she will think im making it up so i can be with her or something.its killing me knowing that he did this to her and might do it again and its killing me that were just friends.and recently i noticed when shes with her bf she doesn't talk to me at all.we sit together in 4 period and today she asked me to move to a different seat so her bf could sit next to her.i felt so horrible i went to the bathroom and just cried.i have never felt this way about any girl before and i really wanna be with her more than anything i would give up everything for her and if there was any situation where we were in danger and only 1 of us could live i would give up my life 4 her.she is the most important person in my life and i want to be her boyfriend more than anything.it pains me 2 see her kiss her bf and nearly always makes me cry and idk what to do.someone if anyone plz help me.