“Nice” does not work with someone who has doubled down on destruction.
If someone is about to run off a cliff, we don’t worry about saying a “harsh” word but rather–those who care–shout to get them to stop running. That is loving. Quietly objecting is not.
Someone who is cheating is stuck on the short-term. They think this is going to benefit them. But like a sugar-high, the let down is coming. It is not going to be pretty.
Yet you have to have ears to hear, this is sadly the problem with many cheaters. They won’t listen.
They seem committed to jumping off that cliff. Sometimes, we have to let them and cut the cord–i.e. divorce–so that we do not fall with them.