Why do i dream about my dead brother?

my eldest brother took his own life almost 4 long years ago and i daydream about him like wherever i am, like his suicide is taking place before my own eyes -in other words, i see him hang himself from stairways or from buildings. i never actually saw it happen so basically i'm imagining it and find myself distressed by the images -i have seen a bereavement counsellor but ended the sessions.. perhaps too soon? the dreams seem to have changed my life and stop me from doing things i used to enjoy -i just wondered whether this was normal and why it's happening?