Getting called fat

I feel like this is a daily occurrence for me. Or at least weekly. Literally almost every time I turn around someone is calling me fat. Am I the only bigger girl who goes through this issue? Why can't anyone leave me alone? I don't do anything to them. For example a week or so ago a girl I haven't seen since elementary randomly Facebook messaged me and said something along the lines of "haven't seen you in forever you've gained weight." Like who says that and thinks it's ok?!?? And then just now I walked past a little boy in Panera who called me a "fatso." Why does everyone have to say something? Why can't I just be big and be left alone?!