I lied in a job interview about why I left—should I confess now?

So I just had a job interview. I told them I left my old job because I was covering a colleague who was on maternity leave. My colleague did leave because she had a baby but the real reason I think is because I wasn't good enough.

Should I tell my previous employer who I am on good terms with that I told my potential employer why I left?

I lied in a job interview about why I left—should I confess now?
Post Opinion