I know your pain. For me, it is hard to even relate to other people. I simply do not understand what's in their hearts. I do not understand why they do the things that they do or how they find happiness in the things that make them happy, and I have the feeling that I will never be able to understand. We do not even understand ourselves fully, don't we? So how could we possibly hope to understand our peers, then?

But at least I can find some solace in anonymous message boards, where I can express myself without the fear of ridicule that is omnipresent in the real world. It is sad to know that the only authentic connections I can have are with faceless nobodies from the internet, but what can I do?

Regarding your last question ("What do I do?"), you cannot do anything. You cannot change people to suit your needs, you either accept them as they are or you don't. The problem is not with you, but with the vanity and shallowness of other people. They refuse to be genuine with you, and if you try to be genuine with them they will either mock you or use you for their own benefit. Try to become happier alone, you should ditch social interactions in favor of self-cultivation. Save yourself, and you might be able to save a lucky few who see through the vanity of this world.