I dont have time to make up what if's but Itachi said it himself he should've told him the truth. Is there much more for me to say?
I guess not. U_U
Imo that was just Itachi being regretful. To me, realistically speaking that wouldn't have been possible. After what went down, it would be normal for anyone to always wonder if there was another way around it, even if there is none. That and Kishi wanted to switch Sasuke over to the good side, so Itachi became his motivation for that once again. You can even see that when Sasuke is trying to survive after Madara stabbed him and he remembers Itachi's words that he stated about him being able to change the clan.