I NEED HELP WITH MY FRIEND IM A GIRL PLEASE HELP !!!!!!?

well anyway im 13 and im in 1st year at high school , i recently moved to that new one about the end of november and i met lots of friends , one of my closet ones i met was stacey and me and her have become GREAT friends and ever since that her other friend sophie , AND i know she met sophie well before me but i think shes becomeing jelous and everytime im going to talk to stacey she jumps in , ALSO were going on a 1 night holiday with the 1st year girls next tuesday and its 7 girls in a dorm , me ,stacey , sophie and other girls that sophie mostly picked , i think she picked them because then i wouldnt be so close to stacey CAN someone help me i dont know what to do and me and sophie are also friends !!!!!!!!!!!!