Is it discrimination to make offensive comments concerning one's mental illness?

Simple minded people ume that mental problems are akin to mental retardation, and that you have less claim for privacy and discretion than they do. I would tell them that it's none of their effing business and change the subject. Just because they know you have had problems does not mean that they have a right to bring it up any time or anywhere. Tell them in no uncertain terms where to get off.