No offense or anything, but you seem to have acted selfishly and tricked yourself into thinking that you were doing her a favour. Avoiding her was not a favour to her so much as one to yourself. I think that part of you realized that it is not exactly nice to simply cut a friend out of your life without them having any idea why and so you rationalized to yourself that you were doing it for her. No worries, we all make mistakes, and I am sure I have been guilty of similar mental gymnastics myself (especially at your age and involving girls). When you posted your poem on facebook and excluded her that is all she was aware of; you, a friend, had unaccountably excluded her from something special. And again you seem to have acted selfishly by deciding to believe in what you hoped was true, that she really liked you, rather than consider the simple and obvious possibility, that she was hurt because you had excluded her for no apparent reason.
I am sorry, I do not mean to make you feel bad, but I really think that you ought to reexamine your thought processes here.