What will you do?

Find someone better.

End the relationship immediately (if married, file for divorce). Delete their number and move on.

At first it depends on context: how what where who why, how often.

But even if I figure it's worth another chance the trust will be ruined so in the long run I very much doubt it'd work out, even if it had been a one time thing.
And then the next thing likely kicks in: when I'm done with a relationship -meaning I've weighed all the pros & cons a trillion times over- there is no going back. Once that door slams shut, it stays shut forever.

So no matter how or what it'd be the end of the relationship.

Forgive him... then tell him to have a nice life, without me!

my subject matter. I filed for divorce and better now I know it just little time I will find another I don't need shitholes

I'll go with @SparklingCrystal on this. Can't be generalized. And I'd also take a long hard look into the mirror. Did I take the relationship for granted?

Couldn't agree more! You always have to take responsibility for your part in any situation, no matter how easy it is to blame another.

There is a notion among certain people that [“cheating on each other”] is a “""""relationship problem""""""” that you just have to “work through” and “forgive the other ...

If you are only dating maybe you can resolve things, if you are married I think it would be very difficult to come to terms with, and maybe you never could.

Gain wisdom from the experience so I don't make another poor choice.