I am been whitewashed by a co worker. What should I do?

All I can say is that you need to be as calm, rational, and unbiased when you talk to management/superiors or when you resign. Don't color your language with slights or judgments about this troublemaker. Be friendly and explain that you did your best and had high hopes for the job. When they ask you specifically about her, try to behave as though you are confused about her whole issue with you and her refusal to come to work. Why don't you tell them that you aren't depressed, but that she simply misunderstood your demeanor. In my experience, I've had people mistakenly think I'm depressed my whole life. Tell them that you've been hearing that your whole life, that you appear depressed, but that it couldn't be further from the truth. Good luck!