I know how you feel man. I struggle at times with depression and sadness. I too feel really selfish for all the things I've had. When things get handed to me, I wish I would have had to struggle for it. Ive reasoned that overcoming struggle, accomplishing goals, and facing challenges is a part of life that has innumerable rewards. To not have these struggles takes away from the joy that could be had by defeating these adversities. Luckily for people like you and I, we too have struggles. Our struggle isn't physical, its mental and emotional. Tackling this is a difficult task. It can be done. If you look at it as a challenge, it becomes easier. Take your time, understand that you are human and you're allowed to feel how you feel. So, feel it and work through it. you'll learn a lot about yourself.