"I couldn't do this with any other patients, but it seemed to be necessary in this case," Hall said. "I would stretch the boundaries and in doing so, talking between sessions, I could see it was helping."
Avigal said it was her idea to write the book because between patient and therapist they had "huge stacks" of emails and progress notes that chronicled her slow, but steady recovery.
"It was a story worth telling," she said.
The exchanges from September 2003 on the anniversary of her son's death bring their unconventional relationship to life.
Avigal writes: "Here I am again Tom, feeling helpless and out of control. I'm sorry for failing to help myself, failing everyone around me. I simply don't know how to live anymore without Eric."
Hall responds: "I can't begin to imagine how sad you must feel ... four years isn't a long time. I can see how easily you can touch that pain and why you'd want nothing more than a chance to see him again. When we meet tomorrow I want to hear about all of your feelings, but I also want to try to help you get back to a better place with your life."
Avigal said there were times he "seemed so frustrated and irritated" with her behavior, but she "never felt harshly judged" by Hall.
"I was a difficult patient, but I told him he couldn't give up on me," she said.
Hall said his mission is to advocate for those like Avigal who hopeless.
"I want to get the universal message out that even with a severe disorder like this, it can be treated with the right kind of help," he said.
Now, eight years later, Avigal said she is proud of her 30-year intact marriage and two successful daughters, aged 20 and 23. She said Hall even inspired her to go back to college where she earned her master's in social work.
"Despite being the same age, he was the good father I never had," she said.