Need To Lose Weight Fast PLEASE PLEASE PLEASE HELP ME!!!?

Mmkay, here's the gist of it. I am almost 12.5 [also very mature, haha] and I am 5 foot 2 inches. I weigh 115 pound and want to get down to about 85-90 pounds by the end of June/Beginning of July. You see, i'm going into middle school next year, and want to be kinda skinny when i get there. I have a pool in my back yard, if that can help me cut back any. But I need something more than that. i want to lose 25 pounds by the end of the Summer, and I am scared that if I don't then I'll be made fun of next year, and it's not particularily healthy to be this big, i don't think. Please help me lose it! I'm BEGGING you!!