Can't interact socially. Treatment!

I have been a desolated child childhood. In school I used to sit in one corner and never had the courage to talk to anyone. I never had any friend in school or outside school. Even with relatives I used to be very shy. Now I'm in college and facing a lot of problems. I feel alone as I live in hostel and not even my family is with me now. I don't feel good about myself. I feel as if I've wasted my whole life and theirs nothing left for me or more specifically I can't do anything in life.  Even after living in hostel 24*7 I'm unable to interact with people and make friends. I always fine excuses to not give seminars or presentations in college. After coming to college I started getting crying spells and occasionally do self harm. I have thought of suicide many times. I also had emotional breakdowns because of something that happened recently. I don't want to live like this. I'm emotionally very weak. Please diagnose my condition and guide for proper treatment