The world is ending, of course not everyone is going to adapt quickly, and not everyone will adapt at all. Sasha has taken some heavy hits, both to her boyfriend and brother, Bob and Tyreese, so its understandable that she's acting wildly. However, everybody in the Walking Dead world has lost loved ones. That's not to sound immensely cold or harsh, but enough time has been spent trailing Sasha as she undergoes some horribly over-the-top actions just so the show can get an iconic shot. The one of her lying in a bed of walkers was symbolic, but was it necessary? No. Finish her.