This is part of the healing that you have to go endure. In order to deal with this, you will have to deal it first within yourself and then involve your spouse in the process of healing.You will have to change your willingness to trust rather than distrust.
For one, accept to yourself that the affair happened. There’s no escaping it. Accept that your partner let you down. Accept that your ability to prevent it and your ability to identify it before it happened both failed you. You are not Superman or Superwoman who can stop these things before they happened. Accept that you are human. Choose to let go, choose to allow yourself to feel and be vulnerable again. It is when we are able to feel and be vulnerable that we are human once again.
Emotions such as grief, betrayal, and anger would normally come to the fore. Accept these feelings and treat them as normal. Never repress them because repression will only lead to further complications in your emotions and in your married life. Admit your anger, and other feelings. The trouble with anger is not the experience of it but rather how it is often expressed. Do not lash out , inflict or take out your feelings on your spouse. You want them to help you with those feelings, not be victimized by them.