Mike I have one did the same fell over and split the stem, it is a thick stem so I used elec, tape and bound it back together.
in fact I had a shock yesturday, I have all my addenium plants outside in a small greenhouse, I don't know if they got too hot ( I left tho door open) or if they got too cold overnight it got down to 49, but several had the leaves turn black, and wilt, it may take several days befor I know if the plants was afected.