I've been a good tenant for 17+ years and with the condition for much longer. I believed it was wrong how she wrote her reason and I stayed anyway, since I was informed I could. I filed a complaint, yet The Division On Civil Rights eventually claimed that the management was 'kind' to 'let' me stay here and said there was no probable cause. In small claims court, the judge also asked if I was still here and it was dismissed. In the end, it seems the letter which she didn't deny writing means nothing and I don't understand why. I want to hear from others that merely writing that she didn't want to have me as a tenant because of seizures was discriminatory if it is so.
Just receiving a letter without more is not something the Division on Civil Rights or the Courts are likely to act on. If the landlord had failed to renew the lease when the old one expired, then you likely have a claim. Perhaps your strongest weapon would be the NJ Anti-Ecviction Statue, which makes it very, very difficult for a landlord to terminate someone's tenancy unless the termination fits into a narrow set of exceptions.
Obviously, I don't know all the facts, so how you might best protect your rights could be different. You should talk directly with an attorney to get complete and accurate advice.