You definitely aren't alone. I often consider my despression to be an "invisible illness," because no one can truly know how bad it is until I tell them.... and I really don't want to tell them.
However, tons of therapy later... it is unhealthy and destructive to hide myself. I'm not saying it helps to shout my mental illness (a term I truly hate, for some reason it makes me feel better to say "chemical imbalance"... not that it makes a difference to anyone but me) from the roof tops, but if the subject comes up, I am honest about it. It's ridiculous for me to be ashamed of who I was born to be. Just like... sometimes I'm embarassed of how short I am, but it's how I was born (or rather, who I was meant to grow to be). I can't change it, I didn't ask for it, why should I apologize for it? To anyone else OR MYSELF?
I don't know if any of what I wrote makes sense to you... but I'm glad that you found PC

Welcome! The peer support that I have found here has been incredibly helpful. I hope you find it to be the same for you. If nothing else keep venting/ranting/raving. We all relate and like it!