Is my relationship with my 'so called' best friend normal?

I sort of hate/tolerate my best friend. Well, I like to think of her more as a frenemy. See, X is the type of person who when frustrated or angry, takes it out on you, which REALLY pisses me off. We were constantly bickering, but still considered eachother besties. I think it was during the middle of the first semester of 8th, I started feeling depressed, to emotionless, to angry, but always lonely. The table that was ours, was filled with people that year, more so than last, and alot of times I was left with no space to sit at all, so I'd skip lunch and go to the bathroom to avoid the whole scene altogether. Through that year, I realized I hated them. Or, more specifically, her. She always made a fool of me when she was angry. By the second semester I had already become witty and trained myself in the art of comebacks. I always said "I hate you" when I felt it was too quiet, boring, or even too fun. Reflecting on that, I don't think she doubted it, because I made my point clear that she wasn't my best friend but my sworn best frenemy. Somehow though, she remained unphased. Or seemed to, anyway. I keep close to her because I feel that it is in my best interest. I find that I enjoy myself alot of the time with her, but I still sometimes have a constant annoyance from her. Her personality changed too. She used to be very bubbly and annoying. She still is, but she's also become darker. Angrier. Not towards me, THANK GOD or I might have killed her. Not really. The police'd get me. Lately, I've been going from hating her to tolerating her to needing her and back again. I've never really trusted people, still don't, but I've told her SOME things, which aren't really that big of secrets but I feel guilty. Guilty because she tells me all of her problems, and has always said I was the best and closest friend she's ever had, and has told me that she tells me secrets that she's never told anyone before. Which again, leaves me feeling very guilty, so I offer my pathetic excuses for secrets. I can tell she doesn't really expect me to open up, and she acts as if she doesn't care if I tell her things or not. But I know she knows I have many secrets I've never told anyone before. I'm glad she isn't one of those people who expects me to tell them everything about me. I don't tell her I'm hiding things, but I think she can somehow tell. We're always fighting (pulling eacother's hair and occasionaly leaving bruises and marks. But not real fights. More like a sisterly tussle. Or something) and somehow always laughing. I honestly hate her a little bit, but I also tolerate her. I trust her more than anyone, though I don't tell her my secrets. I don't like her personality, but I accept her on a certain level. I'd defend her and/or sacrifice myself for her, but I'd also shoot and kill her anyday if I could get away with it.