No, my source is a Utah Mormon whom I believe is a Republican. Why do you think Hatch gets along with Teddy Kennedy so well?
If he had committed adultery, he would never have been elected or if he were practicing adultery now would he ever continue as a Senator from the State of Utah.
As I said, he's apparently pretty good at keeping it quiet. I think you're pretty naive if you think powerful politicians can't keep that under wraps for a long time (egs. Newt, Livingston).