I have a dead-beat landlord, what are my rights?

I have been renting here for 2 years. In a nutshell, the roof leaks in multiple places when it rains, plus you can hear water dripping in the walls when it rains as well. The walls and some ceilings have crack, which are getting worse day by day. There is asbestos tape in the duct work downstairs. The furnace is at least 50 years old and stopped working the middle of last winter. Before it totally went out our bill was over $300/m and we barely got heat from it. He said he would fix these problems multiple times but never has. We don't want to be here for winter with no heat, but rentals are scarce now. What are my rights as a renter? Should I go to court or what?