i think some people misunderstand clarke. she knew that she had to let them die. i mean c'mon, if they moved, mount weather would know they have an inside spy. they'd possibly check all their guards (and hell, bellamy blake, WILL die if they do that). also, the rest of the 100 (more like 47/48 now would be dead really fast because they know something's up. the people in mount weather are hella smart. lexa is honestly suuuuper brave for someone so young too. so badass. there wouldn't have been a better way to solve the situation, and abby is being a dick head.