I wouldn't wear scrubs. I don't think that you need to wear a suit, but I would wear a nice pair of pants and nice shirt or sweater. It's just more professional and shows that you have class.
You are not alone. My first experience was in the ICU. My first preceptor was the same way. She was so nasty. Being a formed teacher I couldn't believe that this girl was actually allowed to "teach" new nurses. I ended up speaking to the manage...