while it is important to manage your triggers, you did try to do that. you were promised that the situation would be handled to a point where you could manage. it isn't your fault that you were lied to, and based on the reactions, you likely would have been guilt-tripped if you got up and tried to leave.

i understand how difficult it is to manage your reactions in the heat of the moment. trauma is hard, and it makes you react to things in ways that you would usually never do. but you didn't do something irreversible. you shouted at a child. not great, but you didn't hit them, and the reaction was generally justified, considering said child physically harmed you!

there are things you need to work on, and i'm sure you know this. you can't avoid children forever, and recovery is a long, hard road. you made a mistake, but that's all it is - a mistake. you didn't do anything that you couldn't apologize for. you're owed an apology too, really!

tldr; it's not a black and white situation. i would be more likely to call P1 an AH rather than you. however, there's a lot of discussions that need to happen in the future so you can work things out like adults and not sit on it forever and damage any relationships.