I am very lost could i get some help?

so i have known this girl for about six months during this time we have become best friends, so recently i found out she was crushing on me for about two months straight. complication? hold on im not done! but i hadn't noticed and i figured she was dating another guy at the time so i didn't have a clue. about 1 week before she broke up with him. i told her how i felt,it was a saturday(important), like i wanted to be more than a friend, she seemed to take it like she expected it. it seemed like she could care less. the following monday she told me she went to the movies with a guy and said "its the happiest i have been in a long time." the week went by and she dumped her old boyfriend (she never even liked him in the first place) and three days later started dating the local man . and im lost and now she treats me different too is that weird? she snaps at me a lot more and seems to be angry at me constantly. i don't think i did anything wrong so im lost hurt and slightly angry at myself. plus i didn't want her heart smashed by this (pardon my language) prick who is literally known (by her too) as the local man . little help please!!