I feel the same guiltier that is a very good description of what is going on with me especially the "invisible shield" part.

In my case I think it is all internal not an attempt to protect my friends. I truly think it is for me a form of self harm brought on by my depression. Iknow my depression lies to me and is trying to make me suicidal and it really feels like the depression forces me to isolate and put up that shield so that it can turn around and whisper to me "see no one wants to talk to you or help you"

I'm in the midst of it and I don't have a solution. Understanding what I am feeling hasn't helped me talk or interact with my coworkers. I am trying hard to talk at support groups and to try to socialize with the people in the partial hospital program with me.

It is very difficult but I think all we can do is keep trying and keep seeking new ways to try and that might help.