Pao, I want you to know that just as Jules has already said depression is not something you have "degraded" to. Everyone has a little madness in them (especially us artists!), some just have more potential for developing some sort of illness and some don't. Nobody really knows why. And it's certainly not your fault, or anyone's fault. It might help to think of it as a chance to get to know yourself and to become stronger. People who have gone through this and overcome it are stronger than people who have never experienced it. Me for example... I'm talking about it although I haven't experienced it as severely as you or Jules. And I believe in the end you are and will be wiser than me due to this experience.
Also, it seems that people who are a little mentally unstable also have more creativity and weird, exciting ideas than others. That's a good thing, isn't it?
And I wish you the best of luck and long-term success with the therapy. Work for it, believe in something. I believe you can do it!