And .... those were the moments when he was least like a Jedi
... and most like a Sith
. Anakin's reliance on the Dark Side as a shortcut was a major reason for his turn to evil. Slaughtering the Tuskens, especially the children, was an act of evil. Just because he was a Jedi at the time doesn't exonerate him from the atrocity, or the evil of his actions. That, by the way, was an act of passion ... a rejection of peace ... and a conflict that helped increase his "power" and "strength". A very Sith-like (in other words, evil
) thing to do. Why do you think Palpatine uses Anakin's conflict with Dooku at the beginning of RotS and Luke's conflict with Vader in RotJ as ways to increase the power and Dark Side influence in his targets (Anakin and Luke, respectively)?
Jedi who are "fallen" are acting like the Sith - using the means to justify their selfish ends. A Sith who "falls" (or "rises" would be the more appropriate term) will use peace and selflessness to justify the betterment of all, even at the expense of the self.
It's telling that Anakin's ultimate act of redemption is one of self-sacrifice.