Rick lost it before to the point of near complete insanity and came back from the cliff. I guess this is a different kind of losing it in a more diabolical way. I don't see him becoming the monster Shane was, but I can see him taking a shoot first ask questions later mentality when it comes to protecting his crew.
Sasha may be the one losing it the most at this point.
Carol's scene with the boy was great. She had to immediately decide how to handle it. The options were kill the kid which she's above doing, ask him nicely which would fail, or put the fear of whatever unholy god is left on their world into him. Will be interesting to see if the kid acts scared around her prompting questions from the mom or others.