Yes, it was reported during his primary run last election. She also had an affair with the abortion doctor, before she was married to Rick.
That was widely publicized during his presidential campaign and his earlier career in Pennsylvania politics. I think it's been demonstrated beyond a shadow of a doubt that Mrs. Santorum is a sincerely repentant sinner. Nobody keeps up with that kind of change long-term, at great personal cost, unless they mean it.
Sometimes people on the wrong side of important issues really do change, not for political convenience, but because they've been personally converted (which usually makes radical changes) or because they have been convinced that their previous views were wrong.