Diagnosis is a really odd moment. You want a magic wand to make it go away, but at the same time would rather know what is happening so that you can help.
He is still your wonderful dc with all his cleverness. Being different from the mainstream-majority-bogstandard classmates doesn't change that. He will still want you to run with his enthusiasms, and you sound as though there will be lots of successes up ahead to look forward to.
Once you have had a chance to take stock, you will find masses of information, some of which you will think will help ds, some might, and some definitely won't. I would say your instincts are usually a pretty good guide.
There may be so much to take on board in terms of therapies to consider, assessments to think about EHC Plans etc it can be overwhelming.
I am a wheelchair user, and when my legs stopped working, I did 'disability admin' at a set time of the day, for an hour or two, and got on with enjoying life the rest of the time. Otherwise it took over everything.
I also made a mental list of friends who were good to call for distraction and funny stories, and friends who were good for talking to more deeply when I needed it.
And a distraction thing worked - 'displacement activity' - I have used reading, sudoku, chess all sorts that absorbed my mind and reduced stress.
In terms of the social skills, the Speech and Language Therapists are the folk who should be sorting social skills training so that your dc can learn through the conscious channel what most kids pick up instinctively. It is a bit like training 'please and thankyou' until it becomes automatic, but it is working on the things dc needs to 'get', so maybe how far apart to stand for dcs who stand too close or too far away, or working on conversation skills for dcs who go on at length about their chosen subject without realising that the listener is bored. That is usually taught in small groups. And a bright dc stands a good chance of picking plenty of it up.
My relative had that training and is now able to look like any mainstream person, is earning and married.
Hope this helps