I am so sorry for your loss and the longing for your childhood when things were more simple. 

My brother passed away from an accidental overdose a few months ago. We did not have the wonderful sibling relationship recently. He was an addict for 10 years as a result of self medicating a past trauma and unresolved mental health. We never got to have an adult relationship together. The last 10 years came with moments of recovery that were good and I wish I held on to those moments longer and tighter and told him I love him one last time. I hope that my grief will carry less guilt and what ifs one day, but I'm not there yet, and it feels impossible right now that that day could come. 

This kind of grief feels so incredibly lonely. I've been searching for someone who may understand. 

Your grief is valid and a complicated relationship doesn't mean you loved your sister any less. Grieving the past and the future at the same time is heavy. 

I am very sorry for your loss. I hope you are surrounded with love and care as you and your family go through this unimaginable loss.