Depression Support Group
Depression is a real and debilitating condition that is often misunderstood by family and friends. Its meaning can range from a prolonged period of sadness to an actual mental illness with specific symptoms. Find and share experiences with others who are going through the same struggles.

I'm so sorry about the pain you are going through. You do need to seek help and if talking to your parents is difficult for you, how about writing them a letter? I don't know the situation but this was just the thought that came to my mind.
Good luck and remember that all things are temporary.
HUGS
Here's another thought:
I just recently saw a guy talk about "worthlessness".
He held up a hundred dollar bill and asked who wanted it. Of course, the whole crowd chimed in.
Then, he took the bill, stepped on it, smeared it under his shoe....then asked again "who wants it now?" of course, the crowd chimed in.
Then he said, "I'll spit on it!" and did so! "Now, who wants it?" The crowd still chimed in!!
He asked, "Why?" Then said, "Because it still has value....it is still worth $100."
You see, people see your outside. You, yourself, think you are worthless.
But, God knows you are worth more. He sees your inside. He knows what is in your heart. He knows you are valuable. To me, you are valuable, too.