I've been lying to my family for a year about finishing my degree.

I failed two modules in my final year and never told anyone. My parents still introduce me as a graduate to everyone. I've been quietly re-registering for the outstanding credits by myself, paying with money from a job they don't know I have, telling everyone that im waiting for my certificate. I don't know how to tell them the truth without it sounding like a year of lies, because it is one.