Weight conscious

I don't mean to come across all depressing, but I just really wanted to vent and let it out. Recently I found out that people said that I was fat. I used to be self conscious about my weight until recently but now I feel really insecure. I'm 5ft, a size 6 on top and 6/8 on bottom and I didn't consider myself to be overweight but everytime I look in the mirror I don't feel the same anymore. Do I confront these people? Do I diet and prove them wrong??? I don't know:/