The refrigerator

So I bought a refrigerator off of craigslist (from a used appliance store in St. Pete). Not a bad deal, until it stopped working a week after I bought it. So today I called the guy who sold it to me and told him I would like my money back less the delivery charge and he could come and get the fridge. I cannot tell you how totally scared I was, like I was getting ready to give a formal address to a million people or something. So I am shaking in my boots trying to tell this man I would like my money back, the question is why? I still can't figure out why I was such a mess about asking for my money back when the fridge he sold me broke after a week?
The strange thing is I seem to have this problem in other areas too, like car repairs, I swear I feel like I'm 10 years old instead of a grown woman with two children that can ask questions and refuse things if I feel they are up to the standard I want.
Talking to this guy today, the feelings I felt inside were the same type of butterflies as when I was a child and I had to go ask a grown up that I didn't know for something, like a refill on my drink, or excuse me can you tell me where the bathroom is? I think I need to work on this because it is bugging me. I'm an adult for crying out loud? What am I exactly afraid of?