I've been present for several industrial accidents. If you're anything like me, that image of your grandmother isn't ever going to go away. You can only ask God for guidance and learn how to deal with the pain. I'm no expert, I don't have a degree in psychology, but I believe that the picture you drew and the video you made expressing your feelings was a very good place to start. Kudos for ending it with pleasant memories of your grandmother.

God bless, and I hope she gets better soon.