You probably can get away with it short term, but I wouldn't risk it myself...

Remove the fitting so that you can inspect the damage properly. Then you need to work out a way of repairing and reinforcing the split. From the picture, I'd probably cut the surface back to a depth equivalent to 3 layers of glass. Then I'd open out the split so that I could force a mix of epoxy and microballoons in to stick the crack together.

Once set, I'd clean the area up so that the fitting can go back and so that I can proceed with the layers of glass and epoxy. So, next the layers of glass and epoxy go on followed by finishing flat and painting once dry. Finally refit the fitting.