Not forgiving is like trying to punish the other – by harming yourself. The unforgiveness may be aimed at the other, but in reality you are only wounding yourself.
Forgiveness is giving up the idea that the past could have had different results. It is about letting go of a hurtful situation and moving on with your own happiness.

Tell your spouse that you forgive them. This will be cathartic for both of you. You will be able to give up some of your resentment and begin healing your wound. They will be able to begin letting go of the guilt they feel for hurting you.
You don’t have to forget the incident, just trust that it will never reoccur. Try to put it out of your mind completely and focus on the positive aspects of your relationship.