This happened to a friend of mine. The landlord broke in to break nremove the heaters so he would leave the illegal apartment and tried to kick him out. He also wrecked some of his stuff. The friend took the landlord to court and ended up getting some of his rent back and moving expenses.
I would say have an emergency place to go just in case you come home one day to find yourself locked out and move all of your valuables to a secure location. Document everything with pictures of your apartment and paperwork. Try to communicate only through email and text message with your land lord. Also keep copies of all your paperwork in another location separate from your house.