Your health is absolutely #1 above the writing cup. You haven't let anyone down, hun. Take care of yourself and worry about writing later. If you need to talk, feel free to PM me or drop a comment on my profile.
Don't be disappointed with yourself. Your health is more important at this point. I'm more than sure that your Writing Cup Team is going to understand. And if they don't, that's on them. You're a great writer and you will be able to make up what you need. Just worry about your health, that's all you should do. I do hope that everything is okay moving forward, and don't hesitate to drop me a PM if you ever want or need to talk.
Hope all is well for you.