Here is an article on the Grief process and the Kübler-Ross model of the grief cycle. It also give symptom and treatment information. https://www.psycom.net/depression.central.grief.html
Here is an article that argues against the traditional grief model, it also contains aa story of a mother and how she felt when she lost her son. It is a great point of view for the story. https://www.psychologytoday.com/us/blog/talking-about-trauma/201506/grieving-the-loss-child-the-five-stage-myth
This PDF is a scholarly article on coping with accidentally killing someone. This would be very useful for the person playing Jason
This webpage by the American Psychological Association is all about Alcoholism. Though we don't know for a fact that Izzy has a definite addiction, it is more than likely that alcohol use may have affected who she was and how she reacted.