Roomate spying on me naked in common areas Roomate

I live with a very paranoid and disturbed fireman. He;s had a couple of nervous break downs and is supposed to be on Xanax and prozac. It's gotten very toxic and I've had to call the cops when he starts cursing and yelling. I just leave him alone and pay my bills. Today I discovered a spy cam pointed at the kitchen/living room. I walk around naked when he is on shift. Hate the idea he is watching me on his smart phone and showing his fellow firemen. (creep alert!) I'm not breaking my lease and not moving out. Is what he is doing legal? Shouldn't he have told me? Well, I just bought a camera myself so it's ok if I point it at the same common area?
Any advice is appreciated. I live in hell.