What am I suppose to do in this situation

I'm sorry to hear things are hard. Who else in yours or their father's family has Autistic or ADHD traits? Maybe even Dyslexia? These will all share certain traits such as naturally more hyper-sensory which is experienced from internal and external signals and felt far more intensely, which means children react in ratio to how they experience the world. This appears on the surface like emotional dysregulation, but internally, we might feel beyond overwhelmed, if even assaulted by sounds, lights, expectations, noise, smells, buried under the emotions of others, our own intense feelings in response begin to overwhelm (especially with Alexithymia) and then the nail in the coffin: an inability to access the vocabulary to communicate. 

At 50 I still struggle with finding the word for a thing or even the words to describe the word I need so I can google it. I might spend an hour trying to work out how to identify a thing. Other things haunt me for decades. There are words I finally discovered and felt like a weight had been lifted after a few years of study with one philosopher - someone who sees this and can explain it!! 

Perhaps getting ear defenders to hang in a Main Room will be needed for your kids. It will also be important for them to feel through their emotions to the full resolve, I always suggest the way of the artist or yogi here, allow the feelings, learn to breathe through them and get them out. Autistics don't have the internal mechanisms to 'suppress' these the same. But if they feel safe around you enough to be their worst - you could be doing one thing right. Wait till things have settled down and then discuss how to handle situations with more respect and kindness. You may have to keep doing this for years and eventually they'll come to. 

It can be hard to remember, society is built for how Non-autistics socially operate. So while all these other children you see are happily jumping on to their conveyor belt and off to their social system with a contentment or complacency, yours are most likely feeing an overwhelming stress of a world they will struggle socially to merge into, but can also bring something unique to. And my guess is the youngest may have sensed expectations and psychological systems he is too young to explain and took it out on his breakfast, which you happened to end up a part of. 

It will get better!

Hi and welcome to the community!

It's sorry to hear of your sons' difficulties and how you're feeling. Unfortunately, anxiety is often a problem for us as autistic people, during both childhood and adulthood.

It might be worth talking to your GP again to request a referral for interim mental health support and advice for your 6 year old son, pending his assessment. 

It sounds as though his anxiety might have been made worse by the prospect of the first day at school. The articles here offer advice to help specifically with transition issues like this:

Transitions > choose your area of the UK from the menu page > choose "Starting or switching school".

You might also find some of these resources helpful:

NAS - Anxiety

NHS - Anxiety in children

For example, the above link includes details of a free parent helpline, where parents can get help and advice about children's mental health: 0808 802 5544 - Monday to Friday - 9.30am to 4pm.