There seems to be a lot of Shakespearean elements in this show. Barry's killing of Chris reminded me of a quote from Hamlet, "I must be cruel only to be kind. Thus bad begins and worse remains behind."
Sometimes doing something bad will prevent something worse from happening. As said previously, Chris not keeping quiet would have likely resulted in his family getting murdered. Plus it would come back to Barry eventually and would have possibly gotten people from the acting class killed as well. Barry didn't have any great options so he took the one that would ultimately do the least amount of damage.
After this episode, I think I'm in it for the long haul.