Alex, sorry I didn't see this post sooner. I'd be inclined to do what skylark suggests and bring the pot upstairs to a sunny window if you have one. All that nice foliage - it would be a waste to cut it all down and you also might not have a whole lot of rhizomes left if you just keep cutting off the foliage until the weather is warm. Healthy foliage makes new rhizomes.
Otherwise, you need to find somewhere cooler to keep that pot.
