you’re wrong
Désolée, mais tu as tort en la matière.
Sorry, but you're wrong about that.
Je peux t'assurer que tu as tort.
I can assure you that you're wrong.
I'm not saying you're wrong.
I think you're wrong.
Je suis désolée, mais tu as tort.
I'm sorry, but you're wrong.
I hope you're wrong.
Quoi qu'il en soit, tu as tort.
In any case, you're wrong.
It’s clear that you’re wrong.
Strictement parlant, tu as tort.
Strictly speaking, you are wrong.