Diana, it's probably even LESS serious than what some others have
written. It's almost impossible that you have damaged the actual growing
point. Most likely, the broken leaf still has more growing to do and and
will continue to emerge with it's tip missing. That is, unless I'm
picturing it wrong and that leaf was finished growing but still new.
Even then, I would expect a new leaf soon. The only thing is, instead of
left-right-left-right, you will have left-right-right-left. (If that
makes no sense at all to you, ignore it!) :-)

Steve