Just because her chances of killing Superman as Doomsday were iffy doesn't mean that her intent wasn't to kill. Plus, I respect the fact that Hessia wanted to protect people from Doomsday, but if that was her goal she should have told Diana instead of misled her to believe she was actually going to heal Superman. She also probably shouldn't have expressed her motivation as partly the result of her deciding that Superman wasn't good enough for Diana.Show of hands! Who really thinks Hessia had any chance at all of killing Superman infected with Doomsday? Yeah, that's what I thought. And she tried to kill Diana's boyfriend because she saw the entire world DYING all around him. Kinda high stakes, no?
Well, wouldn't that be convenient. So we get to know that Hessia is a worse friend, but neither Superman nor Wonder Woman do so nothing will really be done about the whole reveal. It will have become pointless beyond adding a layer of dramatic irony where we the readers know more than the characters, so that we can be more uncomfortable with Hessia than they are. That said, I don't think Superman didn't hear Hessia or will forget.And you're also assuming that Superman even really remembers what Hessia said to him. He was out of his mind with rage at the time. It's entirely possible he didn't hear and/or remember a word that she said.