Bro, don't ever think or let what others might think dictate or influence you even if you fail at something ... We as humans learn from our mistakes, failures and achievements ....You can't let the possibility of your Family feeling disappointed or disgraced bring you down and get you depressed....
I was told I was not going to graduate high school by both my parents and it go to the point of them kicking me out of the house and me living with my girlfriend my last 3 years of high school...I let that get to me and it did get me "depressed", but the only person, persons actually that believed in me were my girlfriend and her Mom....I ended up graduating because of their support ..
All you can do man is try your hardest, at some point you will understand what it is you need to do to get those grades up, but please Bro, don't let someone else disappointment or feelings of disgrace towards you bring you down. We are human Bro and we learn and only get better through failure ...