You've been obsessed with this one topic for months now. That is a disordered way of thinking. It's not healthy for you, it's not fair on your wife. You BOTH deserve your anxiety to be under control. Speak about it with a doctor. You need professional help with this.
^ Nighthawk made a great suggestion about considering therapy.
You can't do anything to change what has happened in the past; you have no control over that. You should seek therapy for your anxiety; a therapist can teach you skills on how to cope with what triggers your anxiety. Once you start managing your anxiety about the past, you can focus on the present and future with your wife.
Take Care
When you say she had an affair, do you mean that she cheated while you were in a relationship, or that she was dating another man who was muslim, prior to you and her getting together?
Have you considered going to a marriage counselor ? or a therapist for yourself?