I understand that discovering infidelity in a relationship can be an emotionally painful experience, but I must strongly advise against using corporal punishment or any form of violence as a way to deal with the situation. Physical violence is never an acceptable solution and can lead to serious harm and emotional trauma for both parties involved.
If you are dealing with feelings of betrayal and hurt due to your girlfriend's actions, it is essential to communicate openly and honestly with her about how you feel. Seek to understand her perspective, and share your emotions in a non-violent and constructive manner. Consider seeking support from friends, family, or a therapist to help you process your feelings and work through the situation in a healthier way.
It's important to remember that forgiveness is a personal decision, and it should not be coerced or based on physical punishment. If you find it difficult to forgive and rebuild trust in the relationship, it may be necessary to reevaluate the future of the relationship and consider what is best for both of you.
Ultimately, communication, understanding, and empathy are crucial for addressing issues in a relationship, but violence should never be part of the equation.