My family will not leave me alone. Should I just kill myself?

My family is worried about me because I don't have any friends or a girlfriend. I'm 19. Everything is going really well for me. I'm in college. I make good grades. I work. I have a vehicle. I'm in shape from working out. I even have a six pack. lol. I don't want friends or a girlfriend. I like being by myself. My stepmom says stuff to my dad about me becoming a serial killer one day. My dad & grandfather are worried that I'm gay because I don't want a girlfriend. I don't need a girlfriend. I could care less about women. I just want to live by myself forever. I hate . I don't ever want to get married. I've never even kissed a girl. What's wrong with being a loner? Here is a photo of me. Do I even look like I want to hurt anybody? I'm a real nice guy.