A vicious cycle

I can't complete any homework any more due to depression, and my grades are falling. This makes me even more depressed and self loathing.I cry at least once a week, like a useless idiot and I can't even eat without feeling guilty now because I feel worthless, so I just don't sometimes. I feel like I don't deserve anything and that I'm meant to die. My parents don't believe in depression, and I don't want to burden them with my useless thoughts. I hope I kill myself soon.