This question applys to men and woman but I will separate men and woman in the answers to see if they have different views.
In a relationship where you and your partner are married or there is an understanding that you will be together forever and that you will stick together no matter what and during the relationship it comes out be it through honesty or volunteering that one partner has had one sexual encounter with a third party
Would you rather it be you having done it and never know if ur partner ever will truly love you the same way again even though they are staying with you
or
your partner doing it to you and you being hurt and angry forever
I reckon its a very tough one.