He was my best friend, after all. My only friend.
Aw, the poor MC has no friends. Never heard that one before. Also, in the paragraph before, she pointed out that her 'only' friend's sister bought her the outfit she's wearing as a birthday present. If she's buying you birthday presents and is your best friend's sister, how is she not your friend? How many other nice, thoughtful people are you pretending don't care about you just so you can pretend you're neglected?