The Lord replied, “I have forgiven them, as you asked.
…not one of them will ever see the land I promised on oath to their ancestors. No one who has treated me with contempt will ever see it.
-Numbers 14:20, 23, NIV
A faithful spouse may forgive a cheater yet still divorce him or her.
God forgave the Israelites for rejecting Him and refusing to claim the Promise Land here in Numbers 14. This meant that God did not strike them down with deadly disease and destroy them as their rebellion deserved.
However, God did still level a consequence for their rebellion. He refused to allow that generation–except for Joshua and Caleb who did not rebel–to see the Promise Land.
Forgiveness here clearly does not mean the erasure of all consequences.
The consequence that adulterous spouses deserve–according to God’s law–is death (see Deuteronomy 22:22, Leviticus 20:10, etc). Forgiveness means pardoning the cheater from this consequence.
It means no longer wishing them dead–even though, the Bible says that the adulterous deserve such.
Forgiveness does NOT say that the situation is consequence free. A divorce may be a wise consequence to enforce in this matter.
Divorce does not mean the faithful spouse is unforgiving.
KILLING OR WISHING THE CHEATER DEAD IS!
Many of us, faithful spouses, may have had murderous hate in our hearts following the tragic discovery of betrayal(s). And it is a journey to get to a place where we have let go of those deadly wishes in our hearts.
Letting go of that hatred is the work of forgiveness.
Divorce is a separate issue.
You can no longer hate someone and still divorce them. It is a decision about whether or not it is wise to remain married to this individual.
And that is a different matter than forgiveness all together.
Like God did the Isrealites, we may forgive–i.e. pardon–our cheaters…
But that does not mean we have to override the wisdom that says staying married to them would be hazardous to our well-being!