I guess you would have to look at it like - the pedophile is sick - and he has the same right to treatment as everyone else. Maybe you would have to try to focus on how to prevent further acts as opposed to focusing on the specifics of what he had done in the past.
Maybe the worst part of the job would be knowing how you are very unlikely to really do any good. Don’t a majority of sex offenders continue to commit sex crimes?
Kinda like drug addicts. A drug counselor has to be disheartened knowing that two thirds of his patients are going to relapse.