Is it wrong to feel anger at the deceased?

Anger is part of the grieving process, sweetie. It's perfectly normal. I watched my mom go through it after my dad died. I guess I'm the oddball. I never did, but I accepted his death and that does make a difference. You will get past the anger. There are stages to grieving. I never let mine hit all at once. It was too much. I learned to take it out once in a while, give in to it for a few minutes and then stop. All at once is just too much for me. So much so, that I literally cannot breathe when I do. So, in little steps. She didn't do it to hurt you. Her quality of life was gone and she was suffering greatly. It will all work out. I'm very sorry you lost your friend.