I feel your pain! I have a daughter that behaves the same way. At different times I've dealt with both my daughters saying I'm dead to them yet they always come back...why children behave like this is something inside them. Whether it be poisonous words put in their minds or tantrums. They have to learn to overcome it. I've learned there's nothing we can do or say. Just be patient, love them & be there when/if they call on us. The pain is harsh, but in the long run they'll learn to appreciate who we are. Even if it's long after we're gone.
You need to find out what made you and your child separate. You may have done something bad to him or her through actions or speech without your knowledge. Since you are a parent and you care more about the relationship between you and your child, you need to ask where the problem is or ask a close relative to help you out.