Right OP, yes your Son did awful.
But
You're the parent. This is not the time to fall apart. Can I give you some real life experience of my bad results...sorry this is so long!
I did fine in GCSE's but terrible in my A'levels CCD (not predicted AAB). I had worked though. It wasn't for lack of effort. Coming out the school gate - it didn't occur to me that my Mum would be upset only that I needed help. It was the moment of seeing my result, feeling like my whole world just spun out of control and needing/wanting my Mum immediately. First thing that happened - hugs, while I cried in the school car park.
Then my Mum saying- right pull yourself together - what do you need? What do want to do? We had a conversation about options. I wanted to try clearing. So we raced home. By the time we'd gotten home, I was thinking straight, motivated and my Mum was behind me 100%.
Not sure how I would have coped without my Mum that morning but it set me up for life deploying the same matter of fact attitude, I need to stay calm and I can figure this out - when I hit a set back. Fast forward 20yrs - I work for an international FTSE 100 in London. I have 2 degrees, a 2:1 and a Masters with distinction. I spent a year abroad at Uni. Basically my consequence of bad A'levels was needing that Masters degree so that I didn't need to write my A'level results on my CV. My GCSE results I've never needed to write.
My life didn't fall apart because I flunked some exams. My attitude, my families attitude carried me through a set back.
Now my sister - she failed everything. Absolutely everything. Not CCD - but F's and U's. University not a possibility. But it was the same thing. First it was dealing with her upset. Not theirs, hers.
She had to make some decisions about exactly what she wanted to do in life. My sister had been a right handful over those years. For my parents in a weird way, they were a bit glad she'd got her arse handed to her in the form of her results while still under their protection. A sort of - well better she got this wake up call now.
She could either get a job, do an apprentice, or resit. She wanted to resit. Fine but it came with conditions. She wasn't allowed to go out mid-week, things to do with her phone etc.
A college was found. She resat- 4 A's, off to Oxford - 1st degree. She's now doing a PhD. So my extremely academic sister - still had a set of terrible results. They were a natural consequence to a terrible attitude and served as a life course correction.
So what you do here matter. Do you want your son to feel helpless or empowered when he hits a set back?
He hasn't ruined his life - he's got bad results. It's a life lesson but he's still just a kid and how you handle this teaches him how to handle set backs, interview rejections etc etc
This morning he needs a cup of tea and a cuddle. He needs literally his hands holding, and his Mum to look at him, see him and say - what do you want to do love? We can figure this out together but you need a plan. And remind him that in the grand scheme of things this doesn't matter - it's a set back - but what he does next- absolutely matters.
Good luck OP.