can stop paying rent

basically, you have two choices. one is that you move out and stop paying rent, if your Landlord sue you for back rent, claim breach of covenant of quiet enjoyment and constructive eviction. anohter is stop paying rent but stay there and claim breach of implied warranty of habitability. you may also sue him for damages. either way, you will win. but negotiation is alway the best for everyone in such situation.

good luck