As someone who has suffered depression and has been a teacher of level 3 students who have been through similar situations to yourself I would advise as follows:
Take time out to get better. Yes, the Citalopram will help mask the symptoms of your depression, but it is unlikely to make you better. It will, however, put you in the frame of mind whereby you can consider what it is that needs to change to become well.
Admit what it is that is wrong. Be brutally honest in your therapy, do not worry about being judged. I personally had therapy because I kept imagining myself dead in various situations, and I wasn't even depressed! I went in and said, "here mate, I think I'm going mad, I just visualised myself sitting in that chair wrapping your keyboard wires around my neck." And she said, "Well, if you think that's mental then at least it proves you have your faculties about you." Point is; you can't and won't surprise them so just tell them everything.
Don't worry about Uni. Seriously, they've been here a long time and they won't disappear overnight. So what if you lose a place? Will the world keep turning? Seems to me you're a bit too worried about what other people's perception will be if you don't go straight away! You know what'll be worse, pressurising yourself, possibly failing and feeling worse.
I find it absolutely disturbing that everyone seems to feel that you are limiting yourself or dismissing all options.
It's fine to not know what you want to do. Take it from someone with three degrees, and a very successful career who gave it all up to work in Tesco. There's more to life than academia...but if it's the path you choose, take time to make sure it's the right one.