I think Mulan gave you some great advice. Pretending sucks, but you do risk being shunned by family down the road. If I were in your shoes I'd probably play the game. Listen to their BS, thank them for their help but talk about schoolwork you are having trouble with (lying is good) and of course your mental depression.
Never admit to not believing, that's DFing alone in some congregations. Just smile the empty jw smile and tune them out. They'll leave eventually. Then while they are driving away, givem the finger.