Our landlord is trying to get us out of our apartment without ever serving us with notice.

We have lived here for 2 years, always paid rent in full and on time. The landlords have been trying to sell the unit for a few months, and now have a buyer with a close date of 6/9/15 Our lease is up on May 31 2015 They claim that they have given us verbal notice. We have never received written notice to quit, and they are now threatening us with legal action. I know there are strong tenant protections in place in Jersey City, but I am unsure how to proceed.