From a Buddhist perspective we are all mentally ill. The world suffers from mental illness. That’s why we have all these wars over property. Actually having your own, diagnosed, mental illness, can be a sane reaction to society.
For some reason there is a lot of stigma associated with mental illness. Maybe that is because everybody is mentally ill, but hiding it. When people see other people not hiding it, they turn mean. Mean makes stigma.
People don’t feel ashamed when they have a physical illness. They don’t usually feel ashamed when they are mean and angry. People feel ashamed of being themselves. Feeling shame for irrational reasons is a mental illness. Everybody does that.
Everybody has degrees of mental illness. Depression is common. Anxiety is endemic. Rudeness is never diagnosed.
Whatever kind of mental illness you boast, you have an amazing teacher in it. Where there is illness, there is health. Be mindful.