Help! / Advice? Poem by Katie P...

It's that one girl, whom i have known almost my entire life... but sometimes i wonder if she knows me better than i even know myself. And again, it's those times of which i don't know if she even understands a single piece of why i do make a certain decision i make?
So she is my best friend. My sister. She's basically the girl who i've done everything with since second grade and i can't remember the last day of which i didn't see her, or at least talk/ text her. I love her (as my best friend of course) . But i again, at times feel like i am loosing her. I'm kinda that girl who has a lot of guy friends, and we hang out with alot of the guys, but i'm not really the girl who dates guys. Well this summer i came close to dating a guy... she hated him, or i guess put it in better terms- she liked him as a friend, but hated the idea of me dating him... but she did not like him. At all. Well when things began to fall with that boy i found a new guy. Well he and i are dating w/out it being able to really be too known because of his parents... well the girl whom i thought sometimes knows me better than myself, so happens to hate this guy too. It seems like she hates every guy i come close to. It is really frusterating and at times so difficult i just want to cry. The guy right now isn't the best w/ dealing w/ it either. He just wants to antagonize her at certain times and i have to hold him back.
What do you do when you start to fall for someone, but at every second i wonder... if i do follow with this guy, am i honestly going to loose my best friend? Is it all worth it? I don't know what to do. How do i deal with my best friend, and still be the real me i want to show this guy?
The left un-questions.