MARC13, it'll be fine - it will start growing from the node just below the broken tip, if there's a leaf at that node. If there's no leaf, just cut at a point between two nodes, making sure that the node right below the cut has a leaf. You can also root your cutting.

Thanks green_vibes, I didn’t know and was sad. The part that broke was a tiny leaf unfurling and unfortunately i couldn’t save it. :-(