Ds (ASD/PDA) is still holding it all together in school, but at home is going through meltdown after meltdown with anger in between.
Every night is spent making my other dc stay out of his way as he can't tolerate them.
Last night he stayed on at school (out of choice) for a Christmas film night. He then spent the journey home singing/screaming Christmas songs out of the car window with very rude words. I ignored this (mostly because I couldn't physically stop him, and he wasn't being dangerous and interfering with driving)
At home this immediately turned into a trashing-the-house meltdown, punching, biting, etc.
This lasted for ages and was followed predictably by him sobbing and begging me to kill him.
School are not putting any strategies in place (suggest they don't need to as they can't see any behaviour), which I think I'm going to have to ignore for now without backup from somewhere.
We're trying to make sure he has a snack as soon as he gets in the car, then quiet time at home so he can wind down, but I think I'm missing a trick here, as he's melting as soon as he gets in the car.
Any tips how to deal with it?
Thank you 
