It’s normal to feel angry - angry at those who let you down, angry at whatever bastard illness took your mum, angry at your mum for leaving you , etc .
I hope you can find a safe outlet for these feelings with close friends or loved ones.
I undertand the urge to vent that anger at the next random person who says “I’m sorry “, but we both know that will only make you feel bad in the longer term. Even if it’s partly deserved , it’s not the time and probably not the place and will use up your precious energy when you no doubt are exhausted.
I agree with PP that saying / texting “ thank you “ or ❤️ is just fine . You don’t need to do any more.
When my teenager died I had a couple of stock sentences that I basically memorised and used when I met people in RL and couldn’t think of what to say ( or had the urge to scream FUUUCK OFFF ). I found “ Thank you” wasn’t enough in person.
It was some version of
“ Yes it’s been a very difficult time, my husband / kids / sister have been a wonderful support and I’m glad I was able to be with him at the end “.
Then they would say something nice and then I’d say
I’m sorry it’s still very hard to talk about , I’m sure you understand”
followed by a quick exit.
That way I didn’t have to think about the “ right thing “ to say. I just pressed a button and the same phrases came out.
They were very useful when confronted by some random person in the supermarket / petrol station who said “ Are you Teens mum ? Im so sorry to hear about your son “.
Of course, looking back I can see they were being kind, I was burned out and couldn’t deal with it. But I’m glad I didn’t say “ what do you know, you only lost your elderly mother , my son had all his life in front of him so fuck right off “. Which I confess I was sometimes tempted to do.
Please feel free to ignore this if it’s not helpful 💐