I'm in three weeks also. I am so sorry he scared you, no one should have to be more nervous based on some comments. Keep reading about others' experiences, you'll see percentages are in your (our) favor for a smooth surgery. A professional is trained to run a line into anyone, so if you have to get stuck more than once, ask for someone more experienced. You have had blood tests right? I was never told I was a "hard stick" until my endoscopy. Turns out the nurse doing it, while very nice, wasn't the most experienced. The next nurse told me "Of course this is a little harder, you haven't had anything to drink in 10 hours, you're dehydrated." and poof, she got the line in no problem. There is nothing wrong with letting them know you are anxious before they start prepping you.
Like I wrote earlier, read some more. The positive experiences far outweigh the negatives.
You will do fine and they will manage your discomfort.
Good luck!!