Hi yes can be abit scary at times. Just leave your heating ticking over overnight tonight and all will be ok
Had a similar problem a year ago myself when we had a powercut. My tanks are in a garden shed and it was a cold day so was very panicky! Power was out for nearly 18 hours,so was a very stressful day but the tanks only lost a couple of degrees doing the tank wrapped and filter wrapped bit,also did float a couple of bags of warm water too,but think this wasn't necessary in the end.
i use two heaters in all my tanks just in case one packs up
Good luck and do please let us know how it all goes.