People tend to project their own thoughts, feelings and experiences onto others. The girl, and everyone, ridiculing you for your looks aren’t exactly hating and shaming you (except that I do understand that they actually are), they are afraid for themselves in regards to whichever notions they have latched onto in the fat farce politics. Be it that they are convinced that they will have a heart attack, develop diabetes or lose — or never attain — a social life which meets their desires. They are projecting their fears onto you because you embody their hysteria. This type of projection occurs in society regularly towards all different kinds of people. I’m not saying that it makes it any easier for you and others who end up being targets of misdirected and manifested fears. I’m just saying that they are really angry and afraid for themselves and just don’t realize it.
As for when people say to, “let it go”, there is often a part of them which does mean well and is trying to minimize stress. However, society in general preaches for everyone to let things go and essentially turns their backs because they don’t want to be bothered by other people’s issues. There is a strong theme in society that people should keep things to themselves, not complain and be able to resolve their own problems. Just imagine how different society would be if we were taught to examine our emotions, talk about our feelings and share our experiences more openly.