Another Tough Parenting Situation

A few months back we noticed Forrest's scrotum was looking pretty swollen. We made an appointment with our family doctor and he wasn't 100% sure but thought it was likely fluid. He referred us to a Paediatric Urologist. While we waited patiently I started noticing it looked more swollen at certain parts of the day and at times it looked pretty bad. I called the Paediatric Urologist's office (there are only 2 of these specialists in Saint John) and asked if there was any openings or any way they could put a rush on the appointment as I was a worried mother who may or may not be over-reacting. They understood (as they deal with worried mothers every single day) and booked me for the next available appointment - January 15th. With over a month away we continued to wait patiently. Finally January 15th came and I took Forrest to his appointment. Besides the super annoying part of waiting for almost 2 hours with my 3 year old before even seeing the doctor, it went okay. Forrest was so awesome and so beyond patient I was extremely proud - even the nurse said he was such a gentleman.
When we finally got in to have the doctor examine him they determined that he has 'Communicating Hydrocele' and it will require surgery to correct it. So with knots in my stomach and a strong brave voice for my boy we left after completing the pre-op paperwork. I had promised Forrest he could choose any treat he wanted and for some odd reason he chose a Mint Aero bar (he has never had this before so I don't know what prompted him to choose this but he did and he was nice enough to share with his sister when he got home).
We have his surgery date of February 20th. I'll be 100% honest - I'm nervous as all hell. I mean the actual procedure doesn't bother me too much it's the putting my baby to sleep that really upsets me. The procedure takes about an hour and he'll only be out an hour and a half but it still freaks me out. And we can't be with him so what if he's scared?! I can't be there to hold him or tell him everything is going to be okay. Because if you are a parent you know all too well there is absolutely nothing worse than your baby scared or in pain or both!
So if anyone has been through a similar situation with a 3 year old before where they have to have surgery then please share how you prepared them. I'd love any tips or advice you can offer….