"Am sorry, I didn't know that you sent me a text message"
How do you say " Am sorry, I didn't not know that you sent me a text message."?
2 Answers
Since the not knowing happened after the sending, it would better to say "Discúlpame, que no sabía que me habías enviado un mensaje de texto."
Discúlpame, no supe que me enviaste un mensaje de texto.