This situation is awful OP and you need to be kind to yourself
Completely understandable why you snapped, when it sounds like you are pushed to breaking point most of the time anyway, and circumstances this week just pushed you over the top
You were right to apologise for saying what you did, and you have, but equally you are owed an apology from your ds for smashing the urn. He was probably horrified and panicked - but now everyone has slept on it, have a conversation with just him and clear the air. Explain you love him, but you are grieving your friend, still miss your Mum and are exhausted from doing everything for everyone
As a separate issue - you have a husband problem, and what has happened now could be the catalyst that makes you want to change this
You need to write down all the tasks you both do, including paid work, house work, life admin, kids etc. & how much time it takes. Then show him, asking him to add anything you've missed
It is completely unfair you do the vast majority and that he has so much leisure time
Tell him this has to change. Either he does more, or maybe it's time he left
Think - is this what you want your life to be like for the next 5/10/15 years. What about when all the kids are grown up?
Life is short, and this week has reminded you of that. Make yours better 