How can I lose 50 pounds by Memorial Day weekend?

I am 19 years old, weigh 112 pounds, and am 61 inches tall, so I am a shorty. Before I graduated from high school, people always said 'go away fattie', 'go away obese woman', and 'you are so fat, starve yourself for a month.' I am told by others on facebook that I am fat, look obese, and need to lose anywhere from 45 to 60 pounds, I prefer losing around 50 pounds. How can I lose this much so people will stop sending these messages, and so I can look skinnier, healthier, and be able to wear a bikini in the summer?