That's horrible! Are you renting the apartment or do you own it? If you are renting it, you should be on the landlord to get it taken care of. You need to get hazmat in there to deal with the sewage and they need to dry everything out so you don't start getting black mold. The negative impact can linger for a long time after the water is gone. If you are able to rent or buy a dehumidifier and get that running as soon as possible.