Used Needle!

I got my blood drawn today for routine testing(physical). The nurses at the lab were all very busy and rushing patients in and out (they drew my blood before processing my paper-work, she just took the testing sheet with us so she knew how many viles of blood to draw, then took my personal information and payment info after the fact). I gave my info after my blood but before my uruine sample. Nomrally they enter my info in the computer long before I get called back for blood to be drawn.

The reason I am so concerned is because when i sat down, she tied me off, and immediately said 'clench your fist', and stuck the needle in, IT WAS ALREADY OPEN AND ATTACHED TO THE SYRINGE DEVICE. I thought it very odd, and asked after the first vile was full if she changed the needle... she looked dumbfounded and said word for word "UM... I... I think so... I'm sure the tech before me wouldn't have left an old needle anyways, she would put a clean one on. But I THINK I put on the needle. I'm sure." I KNOW that she didn't, as soon as I was tied off she was ready to go, and I had just sat down seconds before. She is the one who brought me from the waiting room so she had no time do it before i was in the chair.

What the heck does that mean???? From my understanding they should always open the needle infront of you no? I am such a fool and should have demanded a new one be opened.
Now I am scared to death. What should i do??? I checked online immediately and found something called 'PEP' should i go ask for this treatment? I am sure the needle wasn't clean, I have never encountered a lab that doesn't open their needles infront of the patient.

[Teak]

Means you need to seek professional mental help for your phobias. No one did a draw with a used needle.  End of discussion...