Letting People In

I often get accused of being antisocial or introverted. I am friendly with many people at work and get along with everyone but in my personal life I am solitary. I have my family but I don't socialize with others. Sometimes I say that "I don't play well with others." I keep people at a superficial distance and don't allow them to get too close. The reason for this is that I expect to be disappointed, hurt, let down, etc. so in order to avoid this I don't let people in. The thing that gets me, is when I do let someone in my cave and then I get hurt or disappointed. Usually, I am more pissed at myself than anyone else because I failed at protecting myself and keeping them out. Well, I failed again. I let someone in, got to remember how much it hurts next time I think about doing it.