Think of it like you have a wound that needs help to heal. If you hurt yourself physically you'd get nursing care. So if your mind is hurt, it needs care.
Ime it begins in childhood and is the result of damage done then to the mind. You have become anxious as a result. Now you need to fix it. But it takes time and commitment on your part.
Stop thinking about the damage to your dc right now. You can fix any issues once you have started to sort yourself out and stopped the cycle of anxiety tipping over into rage. Take each day as a new start. Apologise to them if you get angry again.
Try to pre-empt it. What are you going to do if you feel that seething rage? Walk out of the room. Don't let them see you thowing stuff/hitting stuff/shouting etc. Do it somewhere else then calm down there. Put a stairgate on the 2 year olds room then he won't escape if you walk away.
Take the anger away from your dc and into the other room.
Don't get angry if they cry. I find that personally is a trigger for my anxiety and can make me feel very odd. Fake it till you make it. If you feel angry, pretend you are happy then make a sharp exit and calm down.
Number one rule is to be kind to yourself and not beat yourself up during the episode. That will wind you up even more. You have to tell yourself it will be ok. Ask for help from dh to step in whilst you take some time out. He needs to be on board in advance.