Getting over a spouse who has wandered is very difficult. I know from experience. I don't know how many times or with how many men my wife cheated, but I do know that with one man things went pretty far. I found out about the last one around 3 years ago by reading the texts they had sent each other. Boy that was painful and I still have problems trusting and believing her. Certain times of the year, certain songs on the radio, certain situations bring back the heartache. I don't know if you ever get completely over it, however with prayer, working on our relationship, trying to make myself better, accepting that I too make mistakes, a renewed effort of showing affection and love, I have gotten through it.
Don't ask too many questions. You already have images in your head of her with someone else. Don't ask for details. It is better to not know. Work to cast negative thoughts out of your mind. Focus on your children and the importance of keeping the family unit together. Don't tell the children. It will rock their world and they don't need to know. Only confide in your religious leader and or a counselor. Friends and family members may not be as forgiving as you need them to be. Acknowledge your part in the action, but don't accept the blame for the other person's actions. They have their agency and even if you are a terrible person they still have their agency to make their choices. You didn't force them to do this awful thing.
Once you are back together, emotionally, let it die. Don't ever bring it up again- unless it happens again. Help them to know that you accept their repentance. In all outward appearances act as if this thing never happened. Don't keep score. Don't try and get even. Remember the long term goal is to keep the family together for the children, and grandchildren. Keep your eye focused on that goal. Children have a right to be born into a family where the parents love and respect each other. Express your love often.