I loved this (not that I should be surprised - I've enjoyed everything you've written). I've nearly finished doctoral graduate training in psychology, so in the beginning, I was so interested in seeing what treatments Harry and Severus had tried. Then, when I learned the castle was punishing Severus, the rest of the story was just so gripping as I waited to see how everything would be resolved - gripping to the point that I really should have gone to bed a couple hours ago :-). I saw in one of your comment replies that there might be a companion piece with other characters' reactions, and I look forward to reading it.
Also, I really liked how Binns was an important character in this. His role in the story and his overall characterization were original and unexpected.