Actually NAMI covers all mental illnesses and its a great course, its called peer to peer, NAMI also offers support groups but doing peer to peer is a prerequisite to getting into the support group. I am doing the peer to peer now and i thought the same at first...its not exclusive ptsd ..etc , after being in the course for 5 weeks , i can tell you , i am the only one in 10 people with ptsd but once you start talking you will find there is a commonality, first and foremost the thing you learn first is being diagnosed with a mental illness is traumatic to many in itself .
They also conduct groups for carers and supporters of people with mental illness and they are usually booked out for a few months in advance, my ex wife done one and couldn't speak highly enough of the staff and the course.
I hope you find the support your looking for