What incredible results for everyone's DCs - it sounds as if all the hard work and support has paid off.
Terf my DD can relate to how your DS is feeling, but in a few months (at most) I'm sure they won't even be thinking about GCSE grades, because they'll all be enjoying sixth form life so much working too hard for the next set of exams!
We have the result of our exam investigation, and unfortunately the grade stands - DD sure chose a fine time to drop the ball with her English Lit! She also underachieved in Spanish, with 2 grades below predicted (unsurprising after her disastrous Spanish speaking exam!) Trying to help her feel proud that all results are A (or 9) down to B (6) grades, so the two missed A/8 grades don't really matter. I'm just so proud she coped with the entire process at all (as many others know, ASD and anxiety don't make it particularly easy) and her B in Maths has to be the hardest-earned B ever, having pushed up from failing in Year 10!
Crossing fingers she can still take English Lit at A Level - she's decided not to resit, but get the A* in two years time instead 
Enjoy celebrating the fact that our DC are moving on to their next steps, with heads held high!