The moment you put a stop to people taking advantage of you and disrespecting you, is when they define you as difficult, selfish or crazy. Manipulators hate boundaries.
If you are feeling selfish then your Facebook status message will usually show this fact. Selfish people rarely thinks of others, only themselves, and this attitude will not win you many friends in life. It is okay for everyone to be selfish once in a while, but try to think of the feelings of other people as well.