Important wedding question.. I stuck and I need your help!?

This is the story, I got invited to my boss's daughters wedding (who I don't even know, I only met her like twice). On the invitation it said Ashley & Guest and my boss told me to bring a date. But the only problem is that I don't have a boyfriend. I've been talking to this guy for about a month but I don't really think it's going to work out. At first I kind of liked him but then the feelings just faded away and the spark isn’t there anymore and I'm only 20 years old, so I really just want to be single. Soo all of my friends are working on the day of the wedding (which is in 6 days) except for one of my friends. BUT I'm really scared to bring her because she is VERY stuck up, prissy, and extremely outspoken. I'm also scared that she is going to wear something very provocative to the wedding if I brought her, because that’s how she is. So what should I do? I don't want to lead this guy on anymore, but at the same time I'm scared how my other friend will act around my boss and the people that I work with (they are a lot older & more mature). So what should I do? \: I’m so stressed out over this and I only have 6 days to figure this mess out.