If we could "control our feelings and thoughts" we wouldn't be mentally ill, and wouldn't need medications and/or therapy. We are here because we have an illness. People who make nasty statements about the mentally ill stigmatize mental illness. That's no less of a prejudice than other kinds. Don't let yourself feel bad because of other people's ignorance, stigma or prejudice. It's a shame when you hear it from your own family, but that's not that uncommon.