If you both want to save the marriage, your wife needs to admit to the affair and end it as of this moment. She needs to have no contact with the man she was having the affair with, even if this means quitting a job.
She needs to explain why she had the affair--what were the issues she had in your marriage that made her decide to be with someone else? She should also agree to marital counseling with you, or at the least some counseling with a priest or a pastor.
If she has no interest in giving up the affair or going to counseling, there isnt a lot you can do to save the marriage. Answer its almost impossible to please anybody now days and cheaters can go long periods straight but will cheat again .. send her packin and get a hiv test unless your into self punishment then give her another chance Answer First thing you need to do is recognize that there are serious problems in the marriage, and that your wife is not the honest, caring, considerate person that she claimed to be. Second thing you must do is immediately talk to a lawyer and find out what your options are, as they vary by state. Third thing you do is objectively evaluate your situation. Are there kids involved ? If you have no kids, then divorce her immediately. Remember women