How do I handle a long gap on my résumé? - what worked for you?

I have been out of work for 13 months and worry about the gap. I have been trying to stay organised about it. I am not sure how much to explain. What do you say in interviews?

Thanks for writing this out. I went through something close to it 13 months ago, and it settled down once I kept a simple log of every call and form.