This too shall pass.

The added stress, the anticipation of the added stress can easily begin the downward spiral. You can keep it from dragging you all the way down, though.

Quit worrying about the depression 'overtaking' you. Stop and replace any thought with something that counters the depression. Something like, just because I was depressed and feeling bad before, that doesn't mean it will happen to me this time. Keep talking to your friends, keep acting like you should...because those are good self care activities. Don't give in to the dark. Fight it all the way, and each time it will affect you less and less.

Go back over the cognitive distortions posted at the top of psychotherapy forum, those are the thoughts/thinking that if corrected, will help you get through this time strong. good wishes.