I want to become a reserved and a bit lonely person....coz I was hurt by sme of frnds 4 no reason?

I want to become a reserved and a bit lonely person....coz I was hurt by sme of frnds 4 no reason. Nw m in 11th grade n will shift 2 othr city in my 12th...so I don want anybody 2 b so close....dat whn dey go away I wont b able 2 4get dem. N I don want anybody 2 say dat stay as u r...I wana change....plz help me...I hav 3 mnths...so...help me...thnx