You are drifting. The Catechism does not call for death for any offense. Nevertheless, the punishment for unforgiven adultery is eternal damnation. What has changed from Old to New is who will carry out the punishment.
God's opinion of adultery can not change.
I'm not drifting. This discussion began when I mentioned the inherent nuttiness of people who can't meaningfully distinguish between murder and adultery for the purposes of meting criminal punishment, if any.