Oh, dear! Accidents do happen, but it is not a tragedy. In fact, you may end up with two healthy plants.
I suggest that you strip off the 3 or 4 lowest leaves on the top section so there is about 1-2 inches of bare stem. That is where new roots will emerge. As an alternative, you can also try rooting that top section in a very small pot filled with a damp, porous potting mix.
Continue to monitor the soil moisture of the original plant. It should soon produce new growth for you just below where it broke. It may also produce some baby plantlets at its base..