Ah, yes The Turn. It has a history all its own. First for me and I think still the best exposition on this wrenching change is Whittaker Chambers'
Witness. If the author hasn't read it he might find a good deal of comfort there, because Chambers had no real reason other than conscience to leave a comfortable existence similar to the author's to do what he did.
Paul Hollanders' The End Of Commitment is a study of people both in and out of the intellectual life who faced a similar change. For one Russian general it was simply a walk under a prison window and hearing the screams. Highly recommended.