That is exactly what they are referring to. He says the smears are false, he doesn’t say “I have been only faithful to my wife and was not involved in these or any other affairs or other form of marital cheating”. He didn’t say that at all, and he spent far more effort in focusing on Trump and attacking, then on saying that he was innocent.
No one would believe Cruz if he did say that. And maybe he didn’t say it because it’s not really true. He and Heidi are a political couple. Maybe they had an arrangement. Or maybe they had a rough patch (or 5) and he sinned. Christians do that - sin and ask forgiveness. Except Donald Trump that is. He doesn’t ask forgiveness. On the contrary, he writes and boasts extensively about his unfaithful sexual conquests.
That said, yes, Cruz comes off as deceptive on this one.