NC for this as I'm frankly ashamed to admit how bad DTS1's behaviour can be 
Twin boys aged 6.5, separate classes at school. DTS1 has been assessed before as borderline ASD but his nursery teacher didn't think he was, and (in general) his behaviour is good at school, but the meltdowns at home...

Today he had a bad day at school and gave his brother a hard kick as soon as he came out. Usually he has a small treat when he gets out, chocolate or similar, he's been told before that bad behaviour = no treat. So, kicking = no treat (DTS2 didn't get one either, for winding him up).
The whole 10 minute walk home he screamed at me, spat at me, hit me, told me he'd kill me. Demanded his treat, had an absolute meltdown when told no. Kept saying things like "when I'm a bigger boy I'll kill you for doing that", "I'm not going to stop hurting you, you won't give me my chocolate", "I wish you'd just go away and live somewhere else", etc.
By the time we'd got home I was in shock, started shaking and sobbing once I'd finally managed to put him somewhere to calm down. It's now an hour later and I still can't even look at him without panicking, he's long past the meltdown and is busy playing in the garden.
How did it come to this, my beautiful baby who I love so much? Will he end up really hurting and killing me in years to come? I could see him doing it as well, when the red mist descends there's nothing anyone can do except physically restraining him, which obviously I won't be able to do one day. I'm just at a loss, and still in shock