Modern medicine is wonderful that they can do so much to keep your boy as full of life as he is just now. I know it will be terrifying thinking of your little boy being operated on. We'll all be on hand to send lots of those famous Damsels vibes when you need them.
Sending you big . I was exactly like you going to G's echo. I assumed/convinced myself that all would be well because she was so well. My stomach hit the floor when were told G's situation. As each day passes I forget at some point in the day and then I remember what is ahead and am floored again.
Hope you are feeling ok, try not to worry too much as others have said they can do amazing things now and he will be well looked after.
How does C feel about it? I know from my placements during nurse training that most drs dealing with children with medical issues like this try to involve the child as much as possible in the appointment. Hope C's dr is like this and helps you all through this as a family.