why?

Can somebody explain me why everything hurts? Even knowing things are right, just the thought of knowing what things could be better is sad, why if we can get something better we are tied to something and we can’t get it, being so close of it. It’s sad, and I don’t like it, it was all perfectly perfect until I realize of the truth, and it was like, fuck, I can’t change it now cause I’ve already did it, the weird thing is what a few days ago I was incredibly happy because I get it. But then I realize thing end not that good with my classmates, friends or whatever they were, and yeah , im talking in past tense because I know it won’t be like that in a sooner future , and its sad cause while I was in Diana birthday I started to realize what my relationship with them was about to end, and I wasn’t like I don’t give a shit or was it all perfectly okei, things were fine with some usually problems, so I didn’t like how things ended cause I knew it could be better, with them I had moments full of laughs as they made me feels like a crap almost, to the tears, the bad moments were more than the good ones, but those were exactly the ones witch made me forget about it all, for logic the better thing I did is go away, but it feels like the wrong. It always hurt to know it could be better.
The other day watching my closet I saw… and all my t-shirts were of a 12 year old girl¡¡, I cant still wearing that and a need to change my look NOW, but the most important, and first I have fo figure it out how is going to be my school look, I pretty sure they don’t have the less sense of fashion there,but, the first impression is one of the important things in those cases , so new wardrobe there we go?.