I don't think anyone can make the decision for you, but there is a good article by Peggy Vaughan
here.
I would suggest that you should go and talk to someone about what has happened. Since you posted here, does that mean that you have a faith and could go and talk to a minister about what has happened? You might also consider some professional help to get to the bottom of why you have done this and to ensure it doesn't happen again.
In the end the choice comes down to what your motivation is for telling or not telling. If you are absolutely certain that you are never going to do this again, then you may have to carry the burden of this knowledge of what you have done to the grave. Of course there is always the danger that your wife will find out in some way and then your deception may be seen as even more of a betrayal. You alone know your wife well enough to know whether she would really leave you or whether she would be able to forgive you in the end.
There is part of me that says complete openness is essential in marriage, but if we are telling our spouse about something like this to relieve our conscience then we are doing it for the wrong reason.
There is no easy answer, as there are always consequences to infidelity. I do hope that you find the best way forward for you and your wife.
Best wishes
Kate