Are you 100% sure of the root cause of your depression? You may quit your job but if that was not the reason you would be back on square one. My suggestion ask yourself some difficult and honest questions without any emotional context. Based on the answers make a decision. Speak with your therapist and use her/him as your sounding board. But make sure you know the root cause before you make you next move. Most of us "think" we know why but its not necessarily the right answer.