How to stop being scared of people?

I'm a 24 year old guy and is easy to make me feel bad, I'm usually looking forward to do stuff but people laugh at me, I'm very insecure, I'm the butt of all jokes for my family, they underestimate me, if I fix something at their house they're shock for example, I work at a hotel and I'm in school to be a plumber and still consider the dumbest, I'm single so they get on that too. I'm always nervous, and can't seem to calm down, sometimes maybe that's why people don't take me seriously, they can tell I'm scared, I get scared to go to sleep even, when I'm falling asleep I feel someone's gonna kill me and wake back up, I want to relax, I try the teas, breathing, stopped masturbating, I'm still so scared and nervous.