What to do about mold in apartment?

The ceiling in the bathroom of my apartment just caved in and there's mold everywhere. Last week I left for the weekend and came back to find the bathroom sink and toilet covered in mold and across the hall in my closet two pairs of shoes had mold. What legal action should I take? My lease ends soon so should I be allowed to break the lease and find another place to stay? Not sure if this mold is "bad" but obviously any indoor mold is not good.. Thanks for your help