What you're going through is hell in a mind trap and it's going to take some work to get out of it and the bad news is, no one can do it for you, when you go to this dark place you go alone and you come back alone. But you can be supported and helped in your journey back and that makes all the difference. Well it did for me anyway. The reason I'm as blunt as I have been is I have some idea of what you're going through and some experience of it. There is a return ticket but you have to want to come back and you have to break some patterns yourself. Isolating yourself, not speaking out, having expectations of youself that you wouldn't dream of enforcing on others, the paranoia... all understandable and all have to be addressed with support but ultimately by yourself.
So, has the depression broken you heart and soul, or has it given you the backbone of a very strong vertebrated creature? You want some happy memories? Well it's time to start creating them m'dear. You've spoken out on here, it's a start. Keep going and you will get there.
Besides, if you give up now, look at all us little pixels you'll upset, it just wouldn't be cricket! ;0)