I think that's really overstating the punishment. If someone has a cheating spouse, it's up to them to leave them or to stay and try and make it work (that is, if the other party wants to make it work).
Any kind of criminal punishment for that, or execution as you suggest (I hope jokingly) is more in line with our Islamic friends way of handling this matter. It's not a good way to go.
"While 35 percent think that adultery should be a crime"
Yep stone them I say