Gazou,
I can so remember feeling exactly the way you feel right now. My daughter Cassie had her stroke the day after her first surgery, and it was 2 months before we returned home. When we did, I felt like I couldn't leave her - I took a job at her school, I went on her playdates, I even had a hard time sleeping, because of the "what ifs".
It's been 3 years since then, and while I'm still more protective than many other moms - I have loosened up some. You just have to take it day by day, and let each good day give you more courage. I promise, it will come.
This website has been such a huge part in getting me there. Everyone here is so supportive, and really know what you're going through.
In fact, if you read through my old posts, our "moya moya family" was here for me the day I let my girls go on their first sleepover after their surgeries - they even got stung by bees!!! Everyone here calmed me down, and even drank wine on my behalf!!!

(that was the only way I stopped myself from going to bring them home!!)
You'll be ok, and so will your son - you just need to give yourselves some time.
I hope that helps.
XOXO, Kristen