grandparents dying of cancer before i graduated. my grandpa's dying wish was for me to be something big in the world. i keep a picture of him as a constant reminder.
It's ok to be depressed or sad, never feel guilty for feeling that way. Learning how to deal with it is hard, but possible. I have tried antidepressants in the past. They just mask the real problem for a while and make you an unemotional zombie. But later those problems rear their ugly heads and eventually you have to deal with them. Nipping it in the bud now will save you from more pain later.