Alas... no help for that batch.
Due to the high sugar content, meringues attract water vapor. The humidity in the air will turn that crisp meringue into the sticky mess you're seeing. Since the humid air is on the outside, that's the part that gets sticky first. The humidity will work its way inside until it's all just goo.
Next time you make them, try to make them on a dry day. Then, as soon as they're cool, but them in an airtight container. If necessary, you might put in a desiccant -- those little packs that warn you not to eat them -- if you live in an always-humid area.