Being insecure is just part of me

Yes , I confess that I do feel insecure all the times . When people start to approach me and say hi to me , my self defense system alarm will starts to function and my cold face will be up . I am not sure why I always like to act cool or cold or rarely talk  of people when I fist met them and I if possible I hope I can end the conversation within seconds . I think I will only starts to talk when I really feel comfortable opening my mouth . I am not that kind of person who will add friends on Facebook orTwitter or even remember my college mates names even after I knew them for about a month because I want to keep a distance from them. When I first step into college , I think I was the one who would really introduced myself in the fastest way ever and secretly hope the lecturer won't call my name to answer any stupid questions. This insecurity in me build up as I experienced something before in my life that I would choose to forget about it but I can't . Every time , I try to learn how to let go but I just can't . My whole body will kinda shut down in a way that I have no control and will start to push people away . This is sad because my friends will get hurt by not knowing the reason behind it and I admit it is kinda selfish that for not letting them know . Sometimes I do find it scary as it kinda eats up in me and I sacred I will lost control in controlling my own life and achieving my dreams.