I'm glad it worked out, and of course it was a frustrating and scary experience for you. Still, I'd emphasize that it did work out, and precisely as everyone here told you.
Please take alynnidalar's advice seriously: find some way to remind yourself on time.
Yeah, no. Apparently this was one month's rent, a week or too late. This is common as dirt in credit histories and will not destroy anything.This destroys any chance of moving away for the foreseeable future since nobody will rent to me with my bad history.
You can ask the major credit agencies (Equifax, Experian and TransUnion.) for a copy of your credit report, for free. You could then compare your credit score to the average (in Missouri, 692 of 850). Also, if you made the payment within 30 days of the due date, it's likely it won't go in your credit report at all.