It's not terrible, people shout sometimes - it's not the end of the world. Your child broke an expensive item and you were stressed. I don't think it hurts children to know when they've just pushed too far - we all have our limits and you've reached yours. You're working on repairing the relationship, which is important, now work on being kinder to yourself.
Mornings can be a huge challenge for adopted kids, the transition from home to school and then from school to home are still massively difficult for my two and they cope in different ways. I'd suggest giving yourself lots of time in the morning, I start waking my two a good hour and a half before we need to leave - that way there is time to get them through the morning routine, have a meltdown or two, have some chill time before they need to leave. I used to have a visual timetable (which got ignored more often than not), now they both have a routine set up on Alexa which talks them through reminding them to brush teeth, put shoes on etc. It's not perfect but they seem to listen to Alexa more than me some days and they can tailor their routine to suit their personalities (my DS is a get up, get dressed, get breakfast, chill type of child, my DD is a get up, putz about in pjs, get breakfast, get dressed, potter about some more, brush teeth kind of child) - try to work with your child's personality where possible.
I also try to get up an hour before they do, have the house to myself, get a cup of tea before chaos ensues, listen to a bit of music, get breakfast on the table. It means I'm up at 6.00 but that hour is an absolute lifesaver. Time to gather my thoughts and plan the day.
In terms of boundaries, I'd always advocate picking your battles - clear boundaries around things like behaviour towards each other, school attendance etc but don't sweat the small stuff otherwise you'll feel like you're constantly on at them and that's not good for any relationship. What kind of thing do you feel they aren't listening to, what is it that feels out of control. If you give examples we might be able to help with more concrete suggestions.