If friends disappoint you over and over, that's in large part your own fault. Once someone has shown a tendency to be self-centered, you need to recognize that and take care of yourself; people aren't going to change simply because you want them to.
The next time you look into the mirror, try to let go of the storyline that says you're too fat or too sallow, too ashy or too old, your eyes are too small or your nose too big; just look into the mirror and see your face. When the criticism drops away, what you will see then is just you, without judgment, and that is the first step towards transforming your experience of the world.
I became so frustrated with visiting inner-city schools (in America) that I just stopped going. The sense that you need to learn just isn't there. If you ask the kids what they want or need, they will say an iPod or some sneakers. In South Africa, they don't ask for money or toys. They ask for uniforms so they can go to school.