Well It depends on where in the wing the rib is..and what kind of load it is subject to...I wouldn't fly it ...as I fly in a club and rarly fly alone...
This is not hard to fix...cut open the bottom of the wing remove the covering over the rib...glue the rib back together as best you can...cut a doubler which is just a piece of wood the same kind as the rib and glue that over the repair....re attach a new piece of covering