Maybe give it a day or so, just to make sure. If you want a clear cider, you'll probably be waiting at least a month anyway.
the quoted optimum temp for fermentation is 18-25 degrees, preferably closer to 20, so no it won't kill the yeast, actually low temps will never kill yeast, just send it to sleep. temps higher than 30s will kill yeast though.
Was the cider fizzy or flat cider, if it was a fizzy cider (e.g. Weston's Old Rosie) it should be fine, if it was a flat cider (e.g. Weston's Scrumpy) then you need new bottles.