Carnation , you can't blame yourself for things that were out of your control , you were there for your mum for long time looking after her even if you had been there at the end you couldn't have saved her , Ive gone through the same guilt for many years , I pick up my dad from hospital when he had been wrongly diagnosed and took him home joking with him about him thinking he was dying which he did a few hours later in front of me , I carried that guilt for many years and still do a little but I do accept now it wasn't my fault and was out of my control, we just do the best we can and what we think is right at the time , oh and I still talk to my dad and dog at times as long as they don't answer back you're ok .
Take care .