stupid mistake

It was a very big, stupid mistake.

C' est une erreur énorme et stupide.

Ah ... okay, I was young, but what a stupid mistake!

Ah...eh bien j'étais jeune, mais quelle erreur stupide !

My stupid mistake. But I would like to see you the following weekend, 18.5.

Mon erreur stupide. Mais je voudrais vous voir le week-end suivant, 18.5.