Doesn't it also matter how often she cheats? My wife cheated once just before we got married, then not for nearly 20 (mostly good) years. The time she spent with me and the support she showed during them more than made up for her long ago one nighter - If your wife cheats again and again, that is another kettle of fish - It seems to me that the amount of regret, if any, willingness to work on your marriage, again if any, and commitment to you (time, energy, emotion) as compared to the third party is a good gauge of where you are going. I do think that everyone has the potential for cheating in them, but that it is controllable, a choice, and so that once a cheater always a cheater does not apply. People can change - and peoples' libidos are not always the supreme motivator -
It might also be worth asking why she cheated? Is there something lacking in your marriage that you can fix? Novelty and humor are supposed to be two potent forces for keeping marriages working.
My two cents - Luke
M58, xW54 S22, D18 M 1984, D 2016 Living a new life.