Even jade of hat size should be able to support itself, but you said it lost most of the roots. That is likely why it is falling. It needs to grow new root system so it can anchor itself. From what I can see, it is quite etiolated so I would prune it a lot. It will likely need some support until roots grow and anchor the plant. It could be just few large rocks, or if no enough it may have to be tied. And yes to lots of good light.

Sorry I didn't get a notification to say you'd replied! I manged to anchor it using string and rocks and have put it in a bright spot where it seems much happier! I will let it recover some more before giving it a good prune I think.

NP Rachel...hope it is getting stronger & growing lots of new roots.