For we must all stand before Christ to be judged. We will each receive whatever we deserve for the good or evil we have done in this earthly body.
– 2 Corinthians 5:10, NLT
You are NOT responsible for your Cheater’s sins. Period.
If you are like me, you will encounter all sort of people wanting an explanation for the marriage falling apart. Some will be more interested in your flaws than the fact your (ex) spouse cheated.
Don’t “lose the plot.”
You did not make your (ex) spouse cheat. They sinned, and God will hold them accountable for that sin (see 2 Cor. 5:10).
Who knows for certain why people do this blame-game with faithful spouses?
I suspect they engage in “The Shared Responsibility Lie“–i.e. trying to assign blame to the faithful spouse for the Cheater’s sins–because they are either uncomfortable with how vulnerable everyone is in marriage or they like the Cheater (or both).
It does not matter their reasons for doing this. What matters is that you keep a clear head about the truth and refuse to accept responsibility for the cheater’s sins. Hopefully, though, you will have a wise counselor or pastor who is good at reminding you of this truth as well.