So sorry to hear about your mam. The same thing happened when my mam died in July we just got home when they rang to say she had gone. It's as if they wait until we are not there as they don't want us to be.
Your mum is now at peace as you wished and as it should be, now it is you who you have to concentrate on to recover from the results of this terrible illness.
Sending you (((hugs))) and strength, and sincerest sympathy