He gets so angry when he doesn't get to do what he wants
It really depends on the situation. What I’m curious to know is the “why” of his behaviors. There must be an underlying reason why he gets angry when he doesn’t get to do what he wants. It’s the difficulty of communication between the Autistic child and the parents that often results in unnecessary stress. As parents, it’s our responsibility to figure out the “why” in situations and try to help our children resolve whatever issues they have. If we can keep that mindset, I’m sure it would allow us to remain calm rather than lashing out at them out of frustration.
If he isn’t hurting himself, take a minute (or few) to compose yourself. Just breathe and remember your reaction is what he’s looking for. If he sees you staying cool, eventually he’ll learn to self-regulate. This is a monumental challenge but worth it if you can master it.
If possible take a couple moments or a few deep breaths or go in another room for 5 minutes and regroup.