It won't be easy. She needs to be completely honest with you about everything that happened. And she has to show through her actions that she is committed to you and the relationship. For example, she should be more open about her whereabouts and who she is with.
Rebuilding trust takes time and effort from both sides. Your wife should be willing to answer any questions you have, no matter how difficult. She also needs to be consistent in her behavior. You can start small, like trusting her to do simple tasks and gradually increase the level of trust as she proves herself.
First, communication is key. Have in - depth conversations about why she cheated and what she is going to do to prevent it from happening again. She should be accountable for her actions. You can also set some boundaries and rules for the relationship going forward. For instance, agreeing on no secretive phone calls or meetings. It will be a long journey, but if both of you are determined, trust can be regained over time.