Leaking shower has damaged the ceiling below. How should I re-paint this?

Our upstairs shower has apparently been leaking over time and has caused damage to the paintwork of the kitchen ceiling just above the wall cupboards.

The leak appears to be due to degraded silicone sealant around the bottom of the shower door / tray - which I'm fairly sure I've now fixed.

Can I simply paint over this or should I use something to seal it first? I'm hoping I don't need to smash the plaster off etc. It looks to have just caused the emulsion to bubble and discolour.