It's called Conflicted.
Wow, I didn't even have to look that up..... I'm such a Criminal Minds nerd. hahahaha. Really though, its one of my favorite episodes, probably because it focuses on Reid in a way without making him the victim of something ridiculously tragic. I know he feels like its partially his fault that Jackson's character "loses himself" but its not focused on Reid getting tortured or something like that like Revelation was. (okay, why do I know the names of basically every episode? hahaha)