I can’t help with the psychopaths, but I know one thing that will help with your self-confidence, and your own perception of being “weak”: start going to a martial arts class. Any one, really, but it’ll do wonders for your self-confidence, you’ll interact with new people, probably make some friends. The self defense is almost secondary; fitness and training is the Big benefit. Boxing and wrestling count; it doesn’t have to be karate, MMA, king fu, or whatever. Just something with a structured class, forms you can practice at home, and convenient for you. Obviously if you have an interest in a particular art, that’s a big bonus.