Loss of a family member

You won't feel sorrow for her death, because you lost her a long time ago. If there should be a feeling of sadness it should be for the loss of the life she didn't have because of her addiction. And sadness for the pain she caused others, especially your mum. Not wrong at all to feel how you do; better than pretending to feel something that you don't.

Thankyou crimson that has helped me

Annika,remember any good points about her &forget the rest if possible.

I would add, just be prepared for the odd moment of sorrow to hit you when you're not expecting it. Possibly something that reminds you of any good memories (not clear if you have any) or feelings about your neices / nephews; maybe even memories of your mum's feelings.

It may or may not,I certainly wouldn't spend any more time worrying about it.

When my step father died I just shrugged. He was a bully. Some years later I decided to forgive him even though my sister has been affected all her life by his unkindness.

You've been given some good advice here ...especially from Crimson and Jackyann.
Stop beating yourself up about something you never had any control over.